That's a really though question because you have kids.
If you didn't any kids, I'd advise you to don't hesitate one single second and tell that woman to go and f>>> herself.
But there are children and you of course want the best for them. The question, that you have to ask yourself is: Is your whore of a wife is a good influence on their life? And if yes, is it worth all the pain that you go trough?
I don't know you as a person and I also don't know your wife. I only know what you wrote in the topic. That's why don't really consider myself capable of giving you an answer to that question. You have to find it yourself.
What I want to give you is advice on how to go on after you chose:
a) Forgive your slut of a wife:
Your wife cheated on you several times and it appears to me that she didn't even try to make a big secret out of it. THAT HAS TO STOP. Just imagine this klische situation: Daddy, daddy, there is a man upstairs and he makes mummy scream.
You should collect evidences of the affairs that your wife had. After you got some evidence, tell her that if she cheats on you again and you find out, you will get a divorce and that she's NEVER gonna see her kids again. The court case would look like that: Loving father forgives wife who has cheated on him several times and who has broken the promise of never doing it again. You could plead that it is unsupportable that your wife would have any more contact with your kids because she is such a bad influence on them.
What you should also do is learn some more sexual skills. There are a lot of helpful guides and material on the internet.
b) Tell that woman to go and f>>> herself
That is what I personal would be more likely to do, because I think she is probably not worth a the pain she causes.
Here, I also advice you to collect evidences to be prepared for a divorce. It's always good to be prepared.
Find somebody new and tell your wife how great the new girl is and how much you enjoyed fucking her, AND FEEL GOOD ABOUT IT (the telling it to her). I got the image that you have been a nice guy and always there for her and that she took you absolutely for granted. You are the man and not her boy-toy.