First off, you are not alone. All of us on this site have been where you are or is currently there (myself included). Acne is a terrible disease and I think dealing with it as an adult is far worse than dealing with it as a teenager (I am 31). First off, quit blaming yourself. Acne is a crappy roll of the die and you have it because of your body. Treatments that don't work don't work because of your body. Keep in the back of your head that thought.
Secondly force yourself to find other qualities you like about you outside of acne. Also avoid mirrors.
Thirdly, don't isolate, even if you're just inviting a friend over, long periods of time alone are the worst thing you can do
Hugs from NY and if you ever need to talk PM me.