My life is over. I'm doomed for life. What am I gonna do?

I don't know you might be able to win her back but it is gonna take time and you are gonna have to make her believe that you won't ever do it again. That is gonna be hard considering you have broke her trust twice. Maybe getting some counseling together might work I don't know but you are gonna have to do alot of soul searching and begging to win her back. Sending showers and gifts might help too. I would just talk to her, if she still actually wants to, and let her know exactly how you feel and what steps you are gonna take to make sure this never happens again.