Divorce, Why is it so hard for me to file?

I am having such a hard time filing for a divorce and I don't understand what the *** is wrong with me, all of the pain and trauma that man has put me through and continues on putting me through, married 26 years and separated for 6 of those years. 4 adult children, 2 he raised as his own, 2 are biologically his. 2 grandchildren. The last 6 years I have allowed him to come and go in and out of my life as he pleases because I am so weak minded and lonely, basically I am just an idiot fool. While I was at an inpatient treatment center, only a 3 month program mind you, he started having an affair with this gross disgusting poor excuse of a woman, moved her in to our home forceing our 2 children out of our home. He stole our home, kept both vehicles, I got nothing of any value, basically robbed me of 20 years of my life. He went on to have 2 children with this horrible woman, both babies were born with drugs in their system and the state took them, she already lost her first 4 children to the state. This woman accuses my husband of wanting to Fu@k our daughter because she's mentally off her rocker, I guess she does things sexually that I myself would never do and has a lot, I mean a lot more experience then I have ever had or that I would ever want to have. My husband will go for days ignoring me, without having any contact with me, I feel like a burden on everyone in my life, I isolate in my room and rarely leave my home. I feel unloved lonely and worthless while my husband cauters to younger woman. I have no self worth because I have allowed myself to be beat down to nothing. I was doing really well about 2 years ago, I was working for a non-profit agency, I didn't have much but was able to financially provide for myself, being a productive member of society and out of the blue I suffered a massive heart attack and had to have 2 stents put in and since then my depression, PTSD and Anxiety panic disorder have reached an all time high. I am a push over and have allowed people to take advantage of me for so long that nobody has respect for me nor do I seem to have any respect for myself obviously. Tomorrow I am going down to the Courthouse to pick up Divorce Papers to finally file but I have done this many times in the past and never followed through with it. What I don't understand is, if I can recognize all of this, I see the issue, I know what I need to do and what I need to stop allowing then why can't I just do it? I am seriously so mentally and physically exhausted, I don't know what to do anymore, I am so drained and I don't think that I can survive much more of anything