Re: Ugly things I did.
Girls aren't as stupid as you think they are.
She chose her friendship with you over all those other relationships. I'm sure those guys gave some indication as to why things ended between them, that they were weirded out by the relationship that the two of you had. These other guys probably didn't mean as much to her as her relationship with you, so she let them go.
Boys are rarely as slick or as smooth or as subtle as they think they are. Girls are the ones that can deal in nuance.
Now she probably let these other relationships go thinking that your possessiveness meant that one day you would be with her, and that you would come to realize that you wanted more than friendship with her.
At some point or another, she seems to have realized that even that lame guy she knew way back when is worth more than you. I highly doubt she is miserable because of you. I think the most that you can do is to help her build a happier marriage. Dredging up old feelings and overcomplicating the situation is not good.
And pray for forgiveness. Change your behavior so that it is more mature and responsible.