You definitely can't say in a marriage such as yours. You deserve to love and be loved in return. Staying together for security reasons is not a good marriage, but a lot of people do it. They usually end up having affairs and things like that though.
Do you have some type of skill or job you can do? You said your kids are grown now, so you won't have to worry about supporting them, only yourself, am I correct? Or, maybe, your children could live with your husband if he is able to support them and you could have joint custody.
I think you should get a job as soon as possible. You will feel much less dependent on your husband. Actually, if you don't have any skills, waitressing pays quite well, depending on where you work. My daughter works at I-Hop. She does the breakfast shift from 8:00 a.m. to about 4:00 p.m., and she made $100 in tips yesterday. She usually averages around $60 to $100 per shift plus her checks every two weeks.
First, you need to be able to support yourself and then you can get your own apartment and start looking out for your own needs and getting some counselling, if needed. They have counsellors who work with people on a sliding scale according to their income.
It's hard to make changes sometimes, but it's necessary in order to grow and become and a better person. Good luck!