Why did my boyfriend do this? Should i trust him?

Okay, sounds dumb. but i met my boyfriend on facebook. We live in completely different towns. We were dating for almost a month & a half before we actually met. Before we met, he would always call other girls hot & that they have nice boobs & bods on facebook. He's done it 3 different times. Everytime i caught him, i told him to stop & he would for a little but then do it again! When we actually started hanging out he told me he realized what a great girl i am & not take advantage of me. He actually stopped calling girls all those things on facebook & also gave me his password so i could check it. Yesterday, there was a carnival being held close to my town. he lives kind of far away but he went. We were going to meet up there, but then he told me he wasn't going, so i told my mom not to take me. then last minute, he told me he was going. I thought he was going to cheat on me if he went by himself without me. So i told him that we might have to break up. But i didnt break up with him. So i didnt talk to him for a few hours when he went to the carnival. I texted him after it was over & asked him if he talked to any other girls & he responded "I asked emily to hook up" (emily = sluttt) they didnt hook up though. His excuse for that was he thought I was gonna break up with him so thats why he said that. Now i have completely NO trust for him & it is literally killing me. I just cant leave him... i reallly like him. What should i do? why does he do this to me ?