Time will heal all wounds.. not

My boyfriend and I were together for 7 months and expecting a child.. 1 month ago I found out that he had been cheating on me for 6 months with the same girl.. Ironically we all worked together. I was so hurt (still am) because he would always say he would never hurt me or do anything to mess up our relationship. It was all a lie. I asked him why he cheated and for so long, he said he doesnt know why. That is the dumbest excuse I have ever heard. I always had a feeling something was going on because he would always have his phone on silent & locked (after I cracked the code, he changed it again), he would never answer his phone, and would always be 2-3 hrs late. I found out because the girl found our house number and told me what was going on. If it had not been for her finding our number he would still be cheating till this day. Im trying to get over it, but Im pregnant with his child, we live together, work together, and cant believe anything he says. I dont think time is healing me, he is still doing things that make me question him. I have forgiven him, but I dont trust him, Im too hurt to do so.