I need advice ladies !!

So I've been with my boyfriend for about 7 and a half months. and like 2 weeks ago I told him that something tragically happened to me, with a Guy. and he made me go through hell to rebuild that trust and bond we had. but I recently went through his Facebook messages and I seen him talking to a female , last month. I mean he was having deep conversations with her, and the thing that had me is when he told her that , he didn't have a girl. What am I to do now. I'm madly in love with him. I confronted him and he said she needed a friend because she was pregnant and going through things. But I honestly don't see why , he had to lie about that.