I was in your shoes 10 years ago. You need to file for separation. Your marriage is not what you thought it was.
 I too was afraid for the same exact reasons. I was a stay at home mom with 4 kids. I thought I couldn't do it.
My saga with him ended with him being killed in an accident 10 years ago and I found that yes, I can take care of my family. It is not easy but you can do it!
He had destroyed my self esteem, continually accused me of cheating, which I was not, and verbally abused our oldest daughter. Me in my own little world did not even see it until he was gone.
Start the process. He is not the man you thought if he has been doing those things behind your back. He is manipulating you and controlling you and you are better than that and do not deserve it. Even if he has never laid a hand on you it is abuse.
Document everything you know of. Get all the proof you can.
You are strong enough to do this. You may be overwhelmed at times .

There is nothing wrong with you except your low self esteem which he stole from you. Been there. But you sound like you are ready to turn things around. The fear is huge and believe me it isn't going to be easy.  Start hiding cash and not in the house where he might find it. Divorcing an abusive man is not easy because he will cut you off during the divorce process as a means of keeping control over you. As long as you can put up with it, start planning your future without him knowing. Cash, job, etc. I recommend buying a digital recorder ($60) and start taping all your conversations if he is verbally abusive. Then when you are finally ready, get a restraining order against him and take the recordings to court with you. They'll prove your case. You will need to cut him off from you completely, and I mean completely, if you are to start healing. All communication at that point should go through your attorney. Do not let him have the chance to manipulate you into taking him back. You raised 5 kids. You are a strong woman. Now start living for yourself and send a clear message to your kids that they should not be in a marriage like yours. And quit thinking there's something "wrong" with you. Read up on victims of abuse. Abusers are who they are because they can convince even the smartest people that they are lucky to have them.