Me and my girlfriend have been through a lot and it makes it so hard for me to trust again. But I really want to stay committed and trust her again. I don't want any stupid answer like start new or forget about the problem because trust me it doesn't work.

I would ask you to come back with more details on your situation,please.

She needs to earn your trust back, prove to you that she is worthy of it... you, just as importantly, must be willing to and patient enough to give her that chance.
Trust is a very hard thing to mend once it is broken and will take a long time. You both have to be very committed to this. You both need to sit down and lay out some ground rules, expectations of each other and communicate above all else!

Helps to know why you don't trust her.