what to do

looking for someone to help me sort this out Well i guess i'll just get right to it. I have been with my husband for about 5 yrs however we have been together for roughly 18 yrs.  We have always had a relationship that depending on what was going on has been either really good or really bad.  Throughout those years he has always been a very controlling, self-centered, negative, and criticizing person.  He has always been quick to put me down or make me feel less than perfect on many occasions.  I have always known that he loves me very much but he has always put that in my opinion behind his negative or self-centered views or desires. these actions have been verbally and mentally abusive.  He doesnt remember how he acted.  A few years ago he decided to leave.  He told me he was not happy and that he didnt want a divorce but he thought that maybe a separation would make us appreciate each other more.  He was gone 10 days and i was devestated.  He eventually wanted to come home and i made all kinds of promises as did he.  Things were good for several months and then we both started to go back to our old habits.  A little over a year ago things got really bad.  I stayed figuing that we would get through this.  finally by the fall i had taken all i thought i could take.  I told him that i no longer cared and he could have his divorce.  I started to plan my exit.  I didnt want to leave at first because i wanted to wait until 'the right time' for me.  right about then he got laid off and the holidays were approaching.  I didnt want to leave then for those same reasons.  Right about that same time he changed - BIG- he started to be very nice to me.  He did a 180 and i spent the next couple months trying to figure out what he was up to.  I didnt trust him.  I couldnt figure it out and i figured i knew him and it wouldnt last.  He has proved me wrong and still is.  I asked him about it a couple months ago and he says that he has had a wake up call and is trying to change.  He wants to appreciate me now and realizes he was wrong all those years.  The problem is that i was pushed over the edge after a year of hell.  The more we talk the more i believe he has changed but i have lost a lot of love for him and desire to be in the marriage.  We had a bad week last week over a job and after a huge fight(rare these days) i had had enough.  I asked for a divorce a couple days later.  He was shocked and devestated and seeing him hurting was excrucitating to me.  We ended up talking and pulled back on the divorce.  I said i would try once more.  I went to counseling this week( i had planned to go before the asking for the divorce anyway) i am so confused.  He really does not want to lose me and  i can see fear in his eyes.  Is it too little too late? How do i know if he has really changed or how long it will last? what do i do about my changed feelings?  I feel like i messed up and i should have left back when it was ugly because now it is hard and confusing and he is different which makes it even more confusing.  Please help.