I'm sure your mom already has her suspicions anyway. Maybe write her a letter to let her in on your secret that shouldn't be hidden from her, unless you feel it would ruin your relationship. She sounds like the type of mom (just guessing here) that will maybe feel a bit upset that she didn't know sooner, but will probably be happy you confided in her. Does your sister know? I don't have kids, but voted yes, as I think it's something that parents of gays and lesbians should know, even if some can't accept it. I think it would be a burden off your shoulders as well.