Would you break up with a guy over this?

I have been seeing this guy for 6 months and everything was good, but then out of nowhere. he has all these issues from the past coming up, and his EX girlfriend has to move in with him.
the reason i am thinking of ending things with him is because he kept her a secret from me and he lied to me. He just told me she was a roommate when it's actually his ex. when we first got together he told me this ex was out of his life and he wasn't in contact with her. i also found out that shortly after they broke up a month later he starts seeing me. i'm thinking of breaking up with him because he lied to me and he lives with his ex now and I don't feel comfortable being in this situation, but i miss him so much.
Would you break up with a guy over this?
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