How long is too long when you're recovering from a past relationship gone bad?

Long story short, the last guy I was with hurt me more than I imagined he could. What he did gave me lasting feelings of worthlessness and really bad trust issues that I had never experienced before. The worst of it hit about a month before I started talking to my current boyfriend, and I've been with this new guy for almost three months. Sometimes things that my boyfriend or the old guy (who sometimes talks to me on facebook) says will trigger those bad feelings that I'm still in the process of recovering from. My boyfriend doesn't understand why I can't get over the past, and he's not the most sympathetic about it. All of his past relationship "issues" were minor and happened over a year ago. He's had time to recover, I haven't. I really like my boyfriend and I've gotten a little better about my past issues, but I don't know when they will go away, if ever. Is this normal? is it okay that I still get bothered by the past and I need time to recover, even if it overlaps with my current relationship?