Ah ha, well, it makes sense you are so insecure knowing his past. I would be, too.

Trust is very important in a relationship. This is something you need to work on as a couple, and he needs to understand why you feel this way. At the same time, constantly being accusational isn't healthy for either of you. I don't know your situation or if he has done anything to change. This is a bigger concern than watching porn, really.

If he is lying and hiding girls from you that is a big red flag.