The life you have now is making you miserable. Ending the marriage and starting a new life may well be miserable, too, at least at first. But that choice may also turn out to give you a new life ultimately that’s peaceful and rewarding. As Sparkle said, that choice has many unknowns, but many of them could be wonderful. You know that staying will be just more of the same.
I don’t recall a single poster here who’s come back wishing they hadn’t ended their relationship. What I do see are many who say they wish they hadn’t waited so long.