I cant trust my husband anymore but i want to make it work, what do i do?

I am 24 years old. I have been married for less than a year. I have two kids (1 and 3) from a previous marriage. When my husband and I were just dating last year, we got along, but clashed at the same time. We were together for 8 months, and then split up. He said he needed to figure his life out, because he did not know if it was right with me. I loved him, and I knew he was my forever, my heart told me boldly. But when we had split, he was with this girl he had already been friends with before we broke up, and she was the reason we broke up. They had sex a couple times, but most importantly, they got along so well. They were a perfect match to say the least, and they were together every day for a month. We did not talk, he tried to call and text a few times, but I was so hurt i ignored him. He got one of his friends to reach me, and said he wanted to meet me one day and to dress nice. I did, of course, and we went and took a ride on a train, to a beautiful town in the north georgia mountains. Everything went perfect that day, no arguing, no clashing, and no Amanda (girl he left me for). He ended up asking me to marry him, and before I could do anything, yes is what popped out of my mouth. It was a very fast process, we went to the courthouse two days later and got married, got a place together. We are still married today, and have still clashed tremendously. He has always been honest with me, at least on important issues, and I trust him to a point, but of course, insecurity is there because he left me before for someone else. We have fun together, but argue alot too. I have tried leaving a couple of times because I made him so miserable. But he asked me to stay each time. We want to be together, but sometimes it is hard to really believe that on his part. Well he went to the store the other night, and he met up with that girl. Had texted her and asked her to meet him there. The only reason I found out is because my ex husband called and told me he saw them together. So when confronted he admitted his fault, but swore it was innocent and only friendship, because they had a good connection for friendship. He had met her once prior to that night, and texts her on a daily basis. What should I do? I want to trust him, but now he is getting angry with me, because Im kinda stuck up his butt, and I am knowingly, just because Im scared he may lie again. I dont want to push him away but I cannot deal with anymore hurt in my life, if Im too loose and easy going and let them be friends, they may decide they want to be more again. I know my husband deserves trust, but when you lie, that trust is gone. Please give me advice. I need non biast opinions. And only serious ones please. and be honest.