From what I've read about your sitch, I don't think contacting OW would be a good idea. But if you do decide to do it don't expect to gain anything, and be prepared for possible backlash. Also, try to be very careful what you say... and realize it probably won't do a thing and you may or may not feel better afterwards.

Any idea why she left the first husband.... Alcoholism, drugs, physical abuse?????

There is no arriving, ever. It is all a continual becoming.