Bad depression ? Long!

So I had my son 6 months ago. At my 6 week checkup my doctor told me I didn't look like myself and she prescribed me anti depressants (Zoloft). I haven't taken it because of the bad side effects I've heard about. Well I've never had depression before so I don't know what it's like. But me and my fiancée have bad relationship problems. He would go behind my back and watch porn knowing I'm extremely against it. I gave him another chance and told him if he ever does it again I'm leaving him. He let me put an app on his phone that would send me an email if he ever looked up anything porn related. Since then, he hasn't watched anything at all.  Well he just got a new phone and refuses to let me put that app on his phone. He says he swears he will never watch anything again but isn't letting me put it on there cause he wants me to try and trust him without that app. He said he wants to help me move on. I get it. The problem is, he won't have sex with me. He tells me he's lost his sex drive because he's always stressed. The no sex started after we had our son. He's a good dad, but he wants to avoid being home with us as much as possible. If we get into the smallest argument he will leave and go to his moms. If I text him something longer than a sentence he tells me "I'm not reading all that". I can't talk to him at all. Whenever I try to he always gets super annoyed and just goes on his phone and watches Facebook videos ignoring me. I've paranoid that he might look at porn again, to me it's cheating. He promises to me that he won't, but he used to promise me the same thing before but kept doing it. He says he didn't know that I would actually leave him and now he sees that and doesn't want to lose me so he won't ever do it again, plus he says he has no want to look at it. We haven't had sex in a while and he hasn't been affectionate at all. He talks me to really nasty and doesn't care. I've been trying daily to have sex but when I do he turns me down. The other night he came in his dream. I woke him up he changed and went back to sleep while I sat there crying thinking "he was having a sex dream with someone else and came but won't even touch me". Later on I tried asking him about it and he kept telling me he doesn't remember the dream. I asked him if it was someone he knew and he said no, so he's obviously lying to me. Then tells me "that's what happens when you don't please me". Everything I do is my fault. He ruined my trust for him and blames me for it. Whenever I tell him I'm scared that he will do it again he tells me "you're just doing this to yourself, I've told you already I'm not going to". Whenever I ask for affection he tells me I just want attention. I feel so unattractive, I feel so ugly, so fat, I hate myself. I don't feel loved or wanted by him anymore. I remember when he used to want me so bad and now he won't even touch me. The past week I've been waking up and just crying about how unhappy I am. I go take a shower just so I can sit in there and cry. Now before you girls tell me to leave him, that's not what I want. I want to be with him, I just want help on how to get through this. I want us happy again, I wanna feel wanted. Don't make me feel bad for being against porn, I'm extremely against it, I won't watch it and I am not okay with my fiancée watching it because to me it's cheating. He ruined my trust for him and I want to try and trust him again I just don't know how. I'm afraid he will eventually watch it again. I just hate the way he treats me, and how he doesn't even want sex from me ever. We can't communicate. I try and he gets angry. We talked about therapy but he says I need to go first because I'm the one with all the issues. Please give me some comforting advice. I'm miserable. I feel weak, sad, unattractive, ugly, and unwanted. I feel lost. No, I'm not leaving him. I want to find a way to get through this. I want my son to have a family. I really need to hear some comforting words. I'm going to start taking my meds tomorrow and see how that goes but I don't wanna rely on pills to feel happy. There are days where I feel like I don't even wanna live. But I love my son way too much to ever do that to him. I can't leave him. I want to watch him grow up and be the best mom. Help 😢