Posting anonymously just case she’s on here!!

So my boyfriend and I have been together for about 3 months and his birthday was this weekend we celebrated his 40th birthday. His ex wife decided to show up and it really bothered me!! They were married for 20 years and have 3 kids(10, 15 and 16) obviously I invited his kids. The surprise party was at his best friends house. I’m assuming his kids invited her. I was upset she was there but like whatever I didn’t want it to ruin his party. I wasn’t drinking because I’m not 21 yet(in about 2 months!) obviously it was his birthday so I didn’t care if he was drunk or taking shots(his kids left at 8 and they started drink drinking at 9/10. I noticed his ex wife taking shots and giving my boyfriend shots trying to get him wasted! He was so drunk he started taking body shots off her 😡 I didn’t want to cause a scene so I told him I was leaving and to stay at his friends house. Well the next morning he didn’t call or text which ok fine I figured he was hungover! When I went to pick him up I noticed his ex wife leaving. Now I’m concerned they hooked up! I’m starting to care for this man but I’m not sure if it’s worth staying in this relationship! I haven’t talked to him about it yet. His party was Friday, Saturday he was hungover and today(Sunday) he spent all day with his kids and family birthday celebration(I haven’t met his family yet we’re still figuring things out) what do you think I should say? Should I bring it up or do you think I should move on and find someone my own age? I am falling for him but I don’t want to get my heart broken!! I’ve met his kids as a friend not the girlfriend which is why I don’t blame them for telling their mom! They’ve been divorced for almost a year. Help what do you think I should do?

Thank you all so much!! I’m going to break up with him! Although I am falling I rather leave now! Thanks for your advice ladies