My life is spiraling out of control...I don't know what to do

I am self-destructive, selfish and irresponsible and I don't know where to turn.I have been blessed with great friends and family but I feel this isn't something I can address with them. I am secretly a depressive (I suspect manically so) and I feel this has in some way led me to make some really bad and shameful choices.On weekends I get drugged up or drunks and have unprotected gay sex with random strangers. I haven't had the decency or courage to get checked in 18 months because I don't want to be told that I have HIV or any number of STI's and that I have likely passed these on to many other men.I feel I am an awful person and every time I vow to stop, after a couple of weeks I'm back to doing it. I think a part of me wants to destroy myself and has stopped caring about my health or anybody elses. But after I have sobered up, I look at what I have done to myself and feel dead inside.I am out of control I think, has anybody else experienced this that can offer advice.