How can I overcome "Performance Anxiety"?!

How can I overcome "Performance Anxiety"?

I'm a guy, 25 and a virgin. I used to believe in abstinence. I had a strict and religious upbringing.

I only tried to have sex a couple of times of times with my gf and I did not have erection. I always get erection when I masturbate or aroused. I was so stressed when I was getting intimate with my gf as she's 9 years older and she was very wild -sexually- when she was younger. Her past stress me out as it was wild, she also cheated before -I still think about it and imagine it a lot- and finally the big fear that she would compare my performance with her many old experienced partners. How can I overcome this anxiety? I don't have any trouble getting erection when I'm on my own or watching porn or even fantasizing about her -which I do a lot. Any suggestions? Ladies, would you leave your boyfriend of a year for that? Or would you wait for him to be ready and help him to be ready? Thanks!

You're letting the stress get the better of you, and to compound it, you're now worried that not getting an erection will push her away.
So the best thing to do is simple, talk to her about this! Tell her exactly what you've said here! Once she reashures you it's fine, then you'll relax and will be fine. Once you perform once with her, you'll never want to stop! Just get past that first time - talk to her about this!