Boyfriend unfaithful

I don’t know how to trust my bf after he lied to me twice about another female. He denied he was talking to her at first. When I say talking, I mean flirting. Then I found texts and said no again. One of the texts were talking about kissing and getting together after work again. Then I asked again and he finally confessed. They work together. How am I supposed to believe that he’s not still talking to her? I love him so much, but idk if my mind can take being insane any longer. I assume the worst all the time.