I don't love him anymore, but don't know how to leave my emotionally dependent husband.?

Weve been 2gether 12 years. I knew aftr 1st couple that I didnt want 2 b with him anymore. 1 of the reasons I stayed was bcuz he basically left his wife for me, so that created a lot of guilt. Don't judge 2 harshly, I was young & stupid. He has always felt inferior bcuz he never graduated, but thru much ego stroking on my part he now has a good job, makes decent $ & feels fairly good about himself - but he would think it was the end of the world if I were to leave. As is w/insecure men, he has always been very jealous, and I somehow have let him trap me into not having a life outside of him. This includes visits 2 my family unless he's w/me. (But he is devoted to me) I am turning 40 in a couple of months, & feel that I cant stay with him 1 more day, w/o giving up my soul, but the 2nd problem, is we work at the same place, so I feel that he will never really be able to let me go, plus we just started remodeling our house. Leaving my job is not an option. How do I find the courage?