First, get professional help and, as MaineLonghorn suggests, check out NAMI.
About your parents: Do you trust them to be there for you? To support, understand and help you in a compassionate, nonjudgmental way? If so, I would urge you to reach out to them. Tell them basically what you told us here. Be prepared for questions, shock, tears and hugs. It sounds like they love you and want to know what they can do for you. If so, you’re lucky.
As the parent of a son who hid his issues, I can tell you that knowing and learning to understand your issues may ultimately bring them tremendous relief – they may suddenly understand all kinds of things that have probably worried them to death. They’re also likely to deeply appreciate your honesty, trust, and the strength you’ve exhibited all this time.
Wishing you the very best.