What should I do about my marriage?

Hi Brooke,
I’ve been married for nearly 20 yrs. and most of those years have been miserable until I started Life Coach training (with another school) about 3 yrs. ago. I realized that I needed to work on my relationship with myself and respecting myself by standing firm on what I need and establishing boundaries. Since then, my marriage went from one where I felt emotionally abused to my being independent and at peace. My husband and I keep a distance from each other. He has never allowed himself to be emotionally vulnerable and our relationship never really deepened even after 20 yrs. together. We have different interests and energy levels so we tend to do our own separate things. Our bond has never been really close and whatever love I might have felt when I got married is now gone after years of abuse and manipulation. We have 2 children 18 and 15yrs. old. One will be in college next year, the other have 3 more yrs. of high school. I’ve thought about leaving him once my oldest leaves for college, but I’m not sure now on the timing, if at all. My marriage is not what I want or hope for, but now, it’s more tolerable than before. In the last couple of months, it has actually been OK. He’s pitching in and doing more around the house. Because of this new development and because I have lots of fear that comes up when I think of being on my own, I’m not sure if I want to leave anymore. I also don’t want to be the one who breaks up the marriage. My husband has always been able to frame situations to his advantage and I think he would use this to further influence the kids to side with him. Am I indulging in confusion because I don’t want to make a decision out of fear or am I worried that if left, it may be the wrong choice? I’d love your help in clearing up my thinking. I don’t know if divorce is really the answer, but my marriage is lacking intimacy on all levels that I’d like to have in a relationship.
Thanks for your help.