I had the urge to destroy myself today.
Why would you want to do something so terrible?
I hate myself for not being enough to please my gf.
Alot of guys feel insecure about their sexuality like you, but tearing yourself apart over it is psychologically unhealthy. Accept yourself for who you are and don't pressure yourself with unrealistic expectations.
I mean she can't rely on me for penetration...
I understand how bad you feel about not being able to perform sexually for your girlfriend. But having these thoughts of harming yourself because of it isn't the way to go about doing things. I would do some research into doctors you could see about your problem.