Florence,
I really like what others have already posted about allowing yourself the room to have these dreams and not feel guilt about them. You obviously really cared for this person at one time and I think it's probably normal for your subconscious to tap into those old feelings.
Perhaps its a coping mechanism to avoid your feelings about his reality because from what you've described it doesn't sound good at all...active alcoholic, out of work, requires supervised visitation of your DD.
Whatever it is, I hope you give yourself the room and space to accept what is happening as being OK. It sounds like you have a new relationship with someone who treats you and your children well, as all of you deserve! That is wonderful.
It's only been about 11 months since I separated from my STBXAH and I don't know if I've gone 48 hours without mourning the person I thought he could be and the life I wanted for our family.
Sending you good thoughts today.