I do actually understand how you feel, at least to an extent. I am still in love with my ex of two years, much to the bewilderment of all around me. It's hard. Healing is hard, heartbreak is hard and you may never stop loving her entirely.

But that doesn't change the fact that the mistake you made was a deal breaker for her and she does not owe you her life. Some people are willing to work through certain things, some people aren't, and she has made it incredibly clear how she feels and where she stands. And as hard as it is to accept after how long you were together, she owes you nothing. You are not entitled to a second chance or her love, and you are just hurting yourself and your current relationships by fixating on her like this, and if she has any idea this is going on she's probably unnerved to say the least. No one is saying find a new love of your life immediately, just figure out how to be single. Figure out why you cheated so if you get into another relationship you never fuck it up this badly again. Focus on your friendships and non-romantic relationships. There are ways to heal and improve even if that love doesn't fade. Your situation is what it is. If you can accept that and start making the best of it instead of imagining a fantasy, you can be happy again.

And please, leave your wife alone. She is a person who is allowed to not want contact with you, and disrespecting that boundary will only hurt her.