Thought I had the best guy ever :(

I met this man three years ago after a horrible abusive and cheating relationship. We have been dating for two years and have a one year old together. He was amazing to me the entire time, always making sure I was happy, great dad to our son and my son from a previous relationship.... yesterday he was swiping through pictures on his phone to show me deer pics he wanted me to frame for Christmas. Well he swiped too far and there was a recent (this past Halloween) pic of his ex in a sexy nurse costume that he got off a mutual Facebook friends page. He is not friend with his ex. I know it’s recent cause she just chopped her hair off. I am seriously fucking hurt. Never in a million years would I ever think he would do that and still don’t know why. He knows he made a mistake and he apologize but I don’t do second chances. I have my ex Chance after chance and things just got bad. I don’t know what to do. I can’t up and leave financially. I’m just hurt I wanna die.