I don't have too much direct advice because I am dealing with the same dilemma. I finally told my wife last month. She is a rock...and very supportive. I've alrady made progress just by telling her.
My parents are a different story. I don't want to throw the negativity on them or make them feel guilty in any way. And yes, I'm still concerned they might see me in a less than favorable light---I know they won't, but I still worry.
Part of me also wants to clear the air to let them know the real reason I may have acted out in the past. It would certainly fill in the gaps for them. At what cost to them? Why let this perp have sway over four people at this point?
It's an issue for T. I don't have the answer, but I want you to know that you aren't alone.