[Reccaman]

I haven't been on here for a while but everywhere i go i don't get answers. Recently i find out my girlfriend of one year's Ex still had naked pictures of her that she sent while they went out. After a small confrontation between them he deleted them and apologized. After a month of not talking he began to text her again and in the beginning she promised me she wouldn't text back but apparently she has and they seem to be on good terms. He's having a party in two days at a beach and she is begging me to go with her but i still don't trust him and I don't know what i should do. i trust her and i know for a fact he still likes her. What should i do?