The Letter-(which is why I am upset and question it all)

Well the divorce petition came 2 days ago and I knew and opened my letter then started to cry all over again seeing it.  He wouldn't look at me..I think he was upset.  He came down a little later with this letter, and for other he called me Dum as a "pet name".  Here is what it says: Dum, I just wanted to write this to let you know how I feel.  I have to say that I am deeply and honestly sorry for all the shit I have caused, done, and said over the last 18 months.  I am at a point in my life that I never dreamed I would be.  A point I don't look forward to.  I look at you everyday and worry for your well being and your future.  I get very upset with myself for ruining yours and the boys lives.  When you asked why I hate you so much, I don't hate you.   I never have and never will.  I can honestly say, (believe me or not) that in May of last year, I looked at all the shit I did and considered stepping away from Christiana and moving on to save our marriage.  I looked at counseling and what we said in there and thought maybe we could move on.  June came and that point was not an option.  I look at our relationship of 20 years and can not say I reagret any of the things we did.  Did we grow apart, or used to each other and take each other for granted?  I think I took you for granted and your trust.  It is that trust that I destroyed when I stepped outside  the marriage.Today we talked about you going to the lawyer, this is the day I dreaded from the time all this started.  I am truly worried for you.  I love you and you are the mother of our children.  It bothers me to see you physically ill and emotionally in turmoil.  Believe me, there have been days (around Christmas) that I just sat and cried at where my life has gone.  Like you said, I want to be friends and civil for the boys and for us.  We have been thru a lot and have been friends for a long time.Again I am so sorry for all that I have done to you and our family.   Me    Well first on this I have to say we started counseling in Nov of 2008 and in May of 2009 he "decided" and "considered" to move on step away to try to save our marriage.  WTF were the first 8 months for....him to fuck her.  It was all a waste of every Saturday for 8 months and at $100 a pop.  I cry upon reading this because somewhere I am sure he is sorry but I don't honestly know if I can believe it.  In my book, even when I found out the second time I wanted him to say he would do whatever it took...not so.  He doesn't get that now I have more worries esp with the children and who will watch them in a pinch..finding a place to live...boxing it all up..the memories.  Now he gives it a thought...I tried to tell him...I tried.  I gave it a second chance although with a lot of apprehension...a lot.  I questioned the texts and my gut and he assured me that it was nothing...I so wanted to believe him and I did and I feel like a fool.  So here is my letter as to why maybe I am making the wrong decision to keep the petition or call it off.  But...I don't think anything can return to anything remotely normal...I will always wonder when the next time will be.  Any thoughts on this letter would be greatly appreciated.  Thanks --Lisa