My personal feeling is that as you come out of your mid-life crisis you are better off feeling crushed, broken and left on the side of the road but free of your MOM than if you have stayed in it.
I did not know I was in a MOM, but in my early 40's I tried to leave. I didn't know what was wrong I just knew I wanted out. I wish I had made it out then but no, and as with so many of us straight spouses I was of course good at maintaining a relationship, we patched things up, we were reasonably happy, it was like coming out of the forest into a stretch of open valley - I am so glad we stayed together I remember thinking at the time. And you know I felt like anyway my run was over and at least I was settled and could do my artwork.
Here's a snapshot of the hell that was to come from the other side of that valley - my 50th birthday, I have shingles and my back is so itchy and I am miserable as all hell. Emotionally I am shot to pieces, all I want is a cat I can love and not allowed that and my 'husbands' best friend, a closet lesbian he's known since school days arrives for my birthday dinner, which I have managed to cook. She stands triumphantly beside him as she presents me with a life-size plaster cast of a cat, making a put-down comment I can't mercifully remember.
15 years on and my emotional strength and health have improved enormously and I am living alone with my cat for 7 years now - see I did go and get a kitten shortly after that day.