Big hugs hun,
I hope whatever you do, that you do it because its the right thing for you hun, if your not happy in the long run it wont necessarily be the best thing for you ds, whether it be with him or without him, its your happiness that matters too, i cant imagine how hard it is being in your situation, trying to do the right thing by your son thats what makes you such a beautiful and special mum,your puting your own needs and wants last, but sometimes we need to make ourselves happy first iykwim,

It sounds to me as though you were starting to enjoy your independence when you were'nt with him, his lack of responsibility and his finance issues seem like a real pita for you hun if he could change this and prove his responsible attitude to his money and his family maby their could be some hope if you think there is some. ultimatly i think deep inside you know what you want/need to do and i cant even imagine how hard it would be to listen to it hun im thinking of you