what do I even do?

So.. I don't really know how to start this but! My husband obviously has a Facebook and an Instagram, well tonight I got a notification on Instagram saying "your Facebook friend *insert husband's name here* is on Instagram as *insert ex girlfriend of 4 years (who took his virginity I might add) name here*... uhhh what?
So I start looking into things and I don't really see anything connecting the two, but when I logged into his snapchat I found he had been snapping other girls, and even had one girl in his phone with a tiara by her name.. then I go over to his stories of people he follow's to find "Booty HQ." Seriously beyond hurt right now. He's military so right now he's away for part of his schooling. I already sent him a nasty text because that really hurt me. Whether that was right or wrong, I did it out of anger. I really don't know what to do now. I don't know if I can trust him if he's talking to other girls behind my back (he made me get rid of all my guy friends when we started dating).. & then his ex of 4 years coming up on my Instagram saying the Facebook for her Instagram is my husband's name. 😣 We've a 2 month old daughter, and whatever this is, I surely never saw it coming. I know he's going to have some excuse. But is there really any justifiable reason for ALL of the above LISTED?