I have to tell you the longer you stay in that relationship if does get harder to leave. I didn't and it has been 35 yrs and it affected my daughter's relationship with me. Children can sense what is going on. I felt like a being on a carosel ride. Do what is best for you and your children. I made a choice that cost me a lot. I have got a better marriage now but it will take time to get back in good gracies with my daughter. Everyone tells it takes time and I am willing to wait.
Good Luck. Cathy56