I was molested by my step father too, for years, but then he left and things were all right after that. But it sounds like yours is still right there and nothing's been processed and still secretive.
In AA we talk about how our "secrets keep us sick". Maybe it's time to really let some light into the room, so to speak. Talk about it with the people in your life. It's safe to talk about it now, you're an adult, they can't hurt you now. You did nothing wrong, nothing to bring that experience on yourself. And you don't have to be around that person, ever. You never have to go back to that.
Like boobybunny said, it's time for some healing.
It took AA and counseling for me to gain some understanding about what I was dealing with in the aftermath of abuse -- and really, most days it just isn't a part of my reality any more. I don't carry the memories around with me, I know what triggers my fears and I either avoid them, or if they come up (as some have recently) I talk to others about it and check my reactions against reality. You'll find your way through it. You're stronger than you know.