My boyfriend proposed marriage but is secretly on Tinder and reconnecting with his exes I feel completely betrayed

I just found out that my boyfriend has been using Tinder behind my back while portraying himself as the most loyal and family oriented guy. He even proposed marriage, and his family knows about us, yet he’s still sending requests to his exes on Instagram. I’m not okay.....I have a splitting migraine and feel so overwhelmed and betrayed(i literally bang my head on the wall)the full story is even crazier, but this alone is breaking me. I trusted him completely and now everything was a lie. If anyone reading this has been through something similar how did you deal with it? Because right now, I don’t even know what to think or feel, or confront or let it go???