How do I get out?

HomeCategory: BreakupsHow do I get out?
TerrifiedTanya asked 2 weeks ago

My husband of 20 years is cheating on me.  He doesn’t know that I know, but I do. I’m sad, but given the history of stress he has brought me over the years, I’m ready for this to just be over. I know it will suck, but I just want to move on.
We have a lot of relationship problems. He suffers from depression or some sort of mental illness. He uses marajuana daily. He also experiments with steroids. He watches a lot of porn, and he has explosive and long emotional rages over what seem to me to be insignificant things (this was true even before he started with the steroids). 
He has never physically harmed me or the kids, but emotionally and mentally I feel abused. I’m a strong and educated woman. I know I will emotionally survive a divorce.
I have brought divorce up to him several times, and each time he falls into a rapid and deep depression and says he will kill himself we divorce. He says he will have nothing to live for. I’m not convinced that he’s not serious. But I don’t know how to get him to leave without things getting dangerous, at least for him.  He’s the father of my children and they ADORE him. 
I have no proof of any of his bad behavior. I don’t want my kids to lose their father or have a poor view of him. As I said, he really can be a great dad, when he’s got his shit together. Most people that know him have never seen this crazy side of his behavior. People think he’s a super nice, laid back, funny guy. I feel like I’m living in a nightmare….
Why does he stay if he’s so unhappy? Why can’t we just split and move forward. How do I get my Affairs in order to divorce him and protect my kids?