Hannalore,
Here is what I did before I left my husband. I did not want to break up my kids home or be hasty so I read this somewhere and it worked.
Keeping in mind that we cannot change anyone else, only ourselves, I gave myself 6 months.
I put 100% into my marriage. I was nice, complimentary, tried not to get mad at the smallest thing, was supportive etc. for six months. Then I revisited.
In my case I had to leave, the writing was on the wall. I had no guilt, no doubt. I had given it my all and it was clear that I had to leave.

Might be something for you to try. As we all know, living with another person, especially of the opposite sex is a real challenge. But if there is more bad than good it's not worth it to stay. Be careful though, sometimes we blame our spouse for everything, including our unhappiness. Our happiness is up to us.

I also did up a pro and con list before the six months and after. I always do this when confused about a decision.
If there are way more cons then pros, then you have your answer.

Hope this helps.
Kate