https://www.amazon.com/Good-Leave-Stay-Step-Step/dp/0452275350
This book is a national bestseller and really helped me to decide on whether or not I should pull the plug on the relationship. I would HIGHLY recommend you buy a hard copy and read it. It's an easy read and probably about halfway through it you'll know what you should do.
As for my opinion? What are you getting out of this? As an educator, I see painful and abusive relationships all the time. I see kids from divorced families all the time. I know the temptation to stay together for the kids is great. But kids aren't stupid. Do they sense the tension of your relationship? Do they sense the lack of intimacy? The stress? If a relationship has turned malignant (no trust, constant cheating, self esteem issues, etc), as it appears yours has become, there's only one thing to do...
Anyway, just my 2 cents.
I'd highly recommend that book. It really helped knock some sense into me at an incredibly emotional time.