LeftTurn, that's a sad story. If it weren't for the fact your ex is already seeing someone else, I'd suggest you tell her what you posted here and try counselling. A lot of making mistakes isn't about the mistake itself but how you resolve (or don't) to get better. Sounds like your ex got tired of waiting. Women in this type of relationship tend to try to make it work beyond the point of no return. By the time they leave, they've given up hope. Its usually hopeless from the man's POV by then, which unfortunately is typically when a man 'gets it'. First wives are often the 'training program' for the subsequent one(s). LOL.
Good news is that 30 is very young. You will love again. Don't feel sorry for yourself, the suicide thing is not going to help anyone (think of your children!). Just use this time to reflect on how things might have gone differently and resolve to be better.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh