You sound like my husband! Are we married?
Take your chance if you think that is going to give you a better quality of life.
My 20 year H did just that and after a couple of years on his own he came back. I didn't want him to because he came back for the wrong reasons; he realized I was actually quite a catch compared to what he was finding out there...He never even acknowledged all the pain he caused and we are still on tenuous terms. Separated but in the same house. Very hard for me.
What I have learned is you can't "make" someone happy, only yourself. If you aren't happy it is your own fault. I tried to make him happy, do everything in my power to give him the life he said he dreamed of, and succeeded. But, he still wasn't happy & is never satisfied. I am the optimist, can be happy, in myself, no matter what. So I do things for me now.
Perhaps you are like me, resigned. I only crave peace now. I am my own best friend and like my own company. But I'm still sad that I married a very unhappy person.
At least you try to help yourself, my H refuses any counseling. We tried that early on and he felt "attacked" he said, because the counselor was trying to help him see things from my side. But then it later came out that my H is ADD/OCD and a Narcissist. Gosh I wish he hadn't hidden that little tidbit of info while we dated. (Yes, he hid it very well)
Best of luck to you. Hope you can "find a happy place" within.

You are definitely not alone, but sound like many of us that just soldier on...