How do I end it with my husband?

I have been married for almost 15 years,and have 2 kids. About 3 years ago I began talking to a neighbor but nothing serious. Well 2 weeks ago the neighbor and I hooked up and I have developed feelings for him. He told me if I got divorced he would be waiting for me on the courthouse steps. I haven't been in love with my husband for many years and I am unsure on how to end it. I'm in school and have no job. He told me if I ever tried to get child support from him he would do everything in his power to take my kids away. Does anyone have any suggestions?