Is he still talking to her

So last month my bf n I took a break for 2 weeks he ended up hooking up with his ex we started hanging out again but not officially back together and he hooked up with her again. We took a break cuz he said I had insecurities and I accused him of messing with his ex cuz they txt four five tones a week and although I found out from her he did show me the txt where he was saying it was a mistake and it can’t happen again and how her number was blocked. The problem is she was brought up in a conversation we had this morning and he said he’ll give it till December she’d hit him up again . I’m on his email and see a message from a few days ago she says she’s still mad at him but too loyal to walk away and that she’s been keeping quiet. Like what does that mean? It was in his recent delete and he didn’t send anything back to her . She’s still blocked on social media and phone number sooo what do y’all think? Why didn’t he tell me she sent that . How can I move forward and trust him.