Trust Issues

I have always have had really bad trust issues and it makes it difficult to be in relationships. I get super paranoid when I don't hear back from you significant other for an hour. Even if he tells me he is busy at work or with school. He has given me no reason to not trust him and yet I still worry he will cheat on me. I have been cheated on before and he is nothing like that person I was with previously. Is there any advice on how to stop my trust issues?