Cheating

My boyfriend kept telling me about a girl hitting him up and said he was not responding and would never cheat and she’s gross and a hoe so I have nothing to worry about. Fast forward we are on a “break” for 2 days (we’re still talking the whole time) and he communicates with her and talks sexually and she sent pictures to him and he lied to me about it and said he didn’t ask for that and she did it on her own and he blocked her. I find out he initiated it and was lying to me and told her we were no longer together and can do things as long as it’s kept low key. Confront him and finally he tells the truth but says it was while we were on the break. So I need advice what to do...do I break up with him or what since we were technically on a break?