Heart broken but doing ok

I know alot of people go through break ups but this one is very hard to understand for me.  I started dating this girl 5 years ago.  She has two little boys that were very young at the time, but we managed to really get alot of alone time during our relationship because the boys have a great dad in which we get along great.  She even moved to my city for 2 years of our relationship to better it.  Our first breakup was 3 years ago in which I moved on and dated another girl for 3 months but I couldnt stop thinking about "her".  She contacted me out of the blue and we instantly started chatting and got back together.  She moved back to her original town after the break up to be closer to her family which is only about 45 minutes from me.  About a year ago I moved in with her for 8 months and it was great but quickly turned bad because it was a very tiny apartment and we just were always arguing over the dumbest reasons, so we both decided to let go and I got my own apartment just down the road from her.  We had no contact for a month in which it was the worst depressing moment and most lonely I have ever felt.  I thought of everything to get her back, sent her flowers, wrote her nice notes in a card, and then wrote a really great letter explaining how sorry i was for everything and that I want to be in her life an marry her one day, it was a very heart felt apology and letter.  She responded very well to this and decided to be friends in hopes to be in a full out relationship again in the future.  about 7 months later we never really made that commitment to each other but we acted as if we were together.  She has always wanted more of a family man out of me which I really tried hard to give her, but me living seperate, in a seperate house, and working different hours has really complicated things.  I admit that I didnt give her all she needed because of this very situation.  I was working toward asking her to move in together again and trying it, knowing that I love her so much and cant live without her.  Recently some things happened in which she convinced herself that I'm not who she wants in life, but at the same time she constently tells me how much she loves me and hates that she has to make this decision, and we need time apart and date other people.  We are each others best friend, and we have been through so much together, and her kids look up to me so much and I love them like they are my very own.  For some strange reason I simply think she wants to marry me and be with me forever but something is convincing her to try this.  I currently am shattered.  I do not know who to turn to nor do I know what to do.  We have wrote emails back and forth stating we love each other and should remain friends and we both have a dog together in which I pay for and cant live without.  She has decided to give me visitations on a weekly visit with him, meaning I keep him for a week and she keeps him for a week, which we have been doing throught us living apart.  This does mean I will see her once a week. 

I am confused as hell.  I want her back so bad.  i want to prove to her that i am the man for her in which i believe she knows is the truth.  I find it extremely hard to move on.  I'm so depressed.  I want to Marry her and spend the rest of my life with her.  What can I do to get her back for good this time.  If she were to accept I would propose to her as soon as I could.  If it is over for good, how do I keep my dog?  What do I do from here on out?  I'm so confused.  HELPPPPPP