Some observations, in no particular order:

When I was considering getting a divorce, a friend who'd recently done it said, "First, do everything you can to avoid divorce. It's approximately ten times more painful than you can imagine." He was right.
Couples therapy. Do It.

A good therapist will help you see your actions, your spouse's actions and your relationship in a new light. If after two or three meetings, your therapist hasn't guided you to at least one new realization, it's not working, try a different therapist.

It may be that splitting up is the right thing to do, but be aware than no matter how unhappy you are with your marriage, and how right it may be to do so, splitting it up will still be incredibly painful.
Through most of our adult lives we have some more or less vague, often changing, image of what our future ought to look like. Getting married tends to solidify that image.

Breaking up the marriage will cause that future-image, that part of you, to cease to exist.

Poof! It's GONE. No more future. All the old dreams and ideas about what you were going to do and be together. Gone.

There will be a void in you that cannot be filled, not by anyone or anything. The void is much larger than the lack of a person playing the role of 'spouse', it's a hole in your identity, an utter lack of future. Only time, new experiences and new and old friends can help you create a new future-image for yourself.

Try to be prepared for this. But don't expect being prepared to help much.

Oh, and if you do split up, avoid Country and Western radio stations like the plague.