I have the same problem granted im a bit younger than you im guessing... but I seem to be unable to go very long without ummm... as you said doing my thing and after i do i feel terrible. I feel filthy and even un faith full to my girlfriend if it was to anything but the thought or a picture of her. I want to stop and every time i say ok thats it im done i slip back into it just like that. I want a way out of this vicious cycle and despratly want help to get over this... lets call it what it is an addiction