2 months after Wedding, what would you do?

Got married August 27th. Best day of my life other than the birth of our daughter 3 years ago! Fast forward to October 30th (2 months after our wedding) we are laying on the couch and a text comes in on my daughters ipad (its linked to his account). I look (don't even open the text) and it's a picture of some girl half naked... Don't even open it because I would NEVER in a million years think he would be doing that. So I pass the phone to him and ask him who that is. My God his face told the entire story....... He said he didn't know what it was or who it was and deleted the text.. after sitting there for a few minutes in complete shock as my heart is beating at 1000mph, I ask again. He said he doesn't know it doesnt matter and it's not worth the fight yadadadaaa. I get up to go sit outside for a minute and he comes out to say that it was an instagram model that he screenshotted and saved in his email (he deleted it from his camera roll then sent to email). I asked which Instagram model because to me, the little glance I had already saw of the pic, it looked like a mirror picture. From what I saw I knew what (little) clothing she was wearing, color, and that it was a mirror pic. After 30 minutes of looking and pounding him about it, he finally confesses it is this girl that comes over MY house to smoke with him and his friends.. he said one of her guy friends sent it to him as "black mail"... I asked why the hell he needed black mail on her and he just came up with some bullshit response.. after a couple hours of going back and forth he finally breaks down and says he screenshotted it from her snapchat! I FREAKED! Snapchat... out of all social media, you decided to screenshot it on something that notifies that person you just screenshotted it..... ugh! He promised absolutely nothing was said.... This pic was screenshotted on Oct. 25th. Obviously very upset, I accept that that was all that was said and that was the end of the night. Mind you, we slept in separate rooms, and we barely talked the rest of the night and the next day. He was super apologetic, crying, saying he fucked up and he would do whatever it took to fix his mistake.... Fast forward to the next day/night (Halloween, 5 minutes before we go out trick or treating with our daughter) I am going through his web browser history and I find google searches of song lyrics, "I like this girl too much, wish I never met her", also found "dentist/teeth pick up lines" "big booty memes" "your ex never appreciated you now he's missing out"... my heart STOPPED! He gets out of the shower and I asked him what this girl is going to school for and he says to be a dentist... (I already knew, just wanted to see if he was that dumb to answer correctly). I flipped my shit and was like why the fuck were you searching this, you said you never said anything to her and all you did was save the picture. He was still adamant on him not ever saying anything to her. He said he searched it, but never went through with it because he came to the realization of the "what the fuck am I doing, this isn't worth it" mentality.... i still don't believe him at this point because he had posted those lyrics on his snapchat and I honestly thought they were directed towards me... how embarrassing, I know..! I started thinking about what other things he's said that could've related to this situation and one morning while out to breakfast he asked me if I would ever dye my hair dark, or dark brown and that he thinks it would look really good on me... 😨 SHE HAS DARK HAIR. Like wtf. We go on another few days not letting it go, not necessarily fighting, but pretty much just me saying how could you do this to me 2 months after our wedding. Why would you do this to me. I never did anything to him for him to do anything like this to me. I have been the best thing that ever happened to him.. Long story, but he had a terrible childhood, his parents suck, and basically me and our daughter are the best things that happened to him... he knows this. So then fast forward to Friday night, 5 nights after the initial "I caught you" night, we are laying in bed and I was just saying nothing was adding up to me and there was more he wasn't telling me. I told him if he did not tell me everything right that second, I was leaving. He confessed that emojis were sent to her (😈😍😫🍑, these ones on a couple different pictures she was sending to him or on her Snapchat story)... he also said he had replied to one of her pictures saying " wish I had that in high school" she had replied "well why didn't you try" and he replied with "i was scared of rejection" or something along those lines... I nearly died. (I know this is nothing compared to actually getting physical and cheating, but I feel this is just as bad because I never thought he would ever do this, especially not two months after our wedding). I asked him when it started and he said probably 2 weeks before the picture was screenshotted... that would lead it back to Oct. 9th which is 6 weeks after we got married..... 😭 he said he caught back the feelings he had for her back in high school... the first cry I belted out was something I had never ever done before. My heart was shattered into a million pieces and my life had just been flipped upside down. I messaged her a few days later to ask if what he was telling me was accurate and she replied a couple days later saying it was nothing and she wasn't the type to interfere with someone's relationship, never mind a marriage. She had a boyfriend and it all was harmless. Never said that he said anything. Fine. Ok. I can live with that. We then take on the next week trying to move on and.... GET PREGNANT! Am I dumb? Like wtf. I've always wanted another, he never really did. But he said this made him realize he was making everything else a priority over me. It made him open his eyes to how he was treating me and not looking at the bigger picture that was right in front of him. I'm not trying to get pregnant to fix things. I fully know that a baby does not fix anything as we now have a 3 yr old and it has been stressful, but nonetheless, we made it through and got married, confidently, so I thought, still madly in love with each other. Doesn't this bitch text me at the end of the week saying she didn't know why she didn't tell me the whole truth when she initially messaged me back. She then began to say he asked for nude pictures a week after we got married, said, "my ashley doesn't smoke maybe you can be my ashley that does😈" she also said he asked to go to her apartment.... I text him telling him I was coming to his job and killing him. Literally freaking out. He calls and i tell him and he said that what she said was absolutely NOT true... he never asked for pictures.. He said one night they were out on the deck and he had said he wished I smoked so we could smoke together on occasion, but then again he liked that I didn't because i would be smoking on all of his stuff all day long... so i can kind of see how she can flip that into saying what she did... he said she asked him to go to her apartment but he never wanted to go to hers. We have an app where we can track each other and he's never been in the town where she lives... he also said I don't see where she's getting two weeks after we got married because she didn't start following him on Snapchat until late September/early October.... idk. I don't know what to do. Nothing got physical but now it's just like I can't fucking trust him. Ever again and I hate that feeling. I also hate living a life where I'm always questioning shit and wondering if there was more to this. Or if I didn't catch it, if it would've gone any further.... what would you do?! Do you think there's more. Do you think this girl is just being malicious?! He swore up and down that he did not say any of what she said the last time she messaged me. I just hate living this way. Always thinking there is more to it, there was more said, or wondering if I didn't catch it when I did, if it would've gone further. He's been good, and proving/showing me that he fucked up really bad and that he wants this to work out and he will do everything and anything to make it work. I just can't get over it. I can't forget about it, it's all I think about on a daily basis. Why me, the timing of it all.... It's like if a male sent me a inappropriate picture I would be like ahhh yeah no I'm all set and unfollow him right then and there and I would tell my husband... I would expect him to do the same. I guess this is just what this girl does is post provocative pictures on Snapchat half naked everyday. So like why not unfollow her after you see that... I just don't get it... any suggestions, advice, suspicions, anything would be helpful.