Hi
I want to add my voice to the "Don't do it!" camp.
You will regret it. She won't feel remorse, she won't apologise. She'll sneer and laugh and bitch with her friends. He's probably done a good job on her anyway in terms of how unstable you are, how crazy you are, how he's better off without you... you don't want to make his job any easier for him!
Having said that, you do need to do something to work it out of your system. My dad left my mum for another woman 19 year ago. In that time, he has married and stayed with the OW - they have 2 children together and are a far happier family than we ever were. She, on the other hand, has had 3 LT relationships, including a second marriage, with increasingly unsuitable men due to her anger and low self esteem as a result of the marriage breakdown. She can't take it out on my dad and his wife because, frankly, they don't care, and her behaviour has been increasingly erratic as she has sought to punish my dad by taking her anger and feelings out on my brother and myself.
This has finally led to her behaving in such an unreasonable way that she is no longer allowed to have unsupervised contact with my children (LA directed not (just) our choice). Add that to the way she's behaved generally over the past 2 decades and we don't want to see her anymore either.
It's sad, but I'm nearly 40. I need to have a life of my own at some point without everything being tarnished by her.
And this is all because she refused to address the way she felt after he left her because there was "nothing wrong" with her. Very sad.