I’m so hurt but fell stupid

I’ve been with my boyfriend for 3 years we have a 7 month old son and I have 5 year old daughter from a previous relationship and lately he’s been complaining about everything I do and a few days ago he try to say someone else had my attention and saying he still has trust issues because of what he ex did and so on I felt like something wasn’t right and come to find out he’s reactive he’s dating account and posted recent pictures of us since we been together and deactivated it thinking I wouldn’t find out I don’t know what I did to deserve this... I had went through his old phone and found out this because something kept telling me he was doing something