Stop, stop, stop. . . beating yourself isn't going to make her come back. I know because I've done this once, uh, twice (pull out billfold), ok, maybe 5 times. But trust me when I say that beating yourself in front of your bishop, in front of your friends, at work or online will only reinforce she has made the right decision. And, yes, this applies to men too.
I might get some heat for this, however, do not—I repeat—do not keep beating yourself. Ok? OK.
Yes, you messed up. Yes, it was stupid. But feel redeemed to know no matter what happened someone else done it worse than you did. . . like me.
So, when you are alone and feel like giving yourself a good flogging, I want you to step into the shower, turn the setting on cold, and if there aren't icicles hanging off your face you aren't doing it right.
After that you are going to man-up and tell her you messed up. This conversation needs to be in person and not over the phone. If the other party insists on this conversation be over the phone don't do it. (There are a million reasons for this and I'm not going to list them all.)
No matter what the outcome is you need to start taking better care of yourself.
And welcome to the club.