It's natural to feel that way, you've been together for along time and although not happy in your relationship, secure. I suppose the good thing is there are no children involved which can sometimes hold back the separation. It doesn't sound like you want the same things and if you want children, then things will only become worse, make the break - that's what I say and find someone who shares the same values. You can only hit your head against the brick wall so many times, Good luck, you deserve it.