Separation and the dependent ADHD spouse

In the interest of my mental and physical health I have decided that I need to care for myself rather than spend all my time supporting my partner.  I am emotionally and physically exhausted and can relate to almost all of the non-ADHD spouses.  I am just going to talk business here since describing the details will just make me more frustrated with what I have lived through thus far.  I am the breadwinner, my husband barely works and only on his own "projects" selling woodworking pieces here and there - but of course the start up costs have been way more than he has ever made.  He has always worked, but not at the same thing and he usually self destructs, etc.   (see I am starting to ramble with the details already).  Anyhow, he has no money saved and no steady job.  If I make him leave he will have no place to go, no family lives near either of us. I am the sole person on our mortgage and pay all the bills, including his. We have one son, who he takes to school and picks up (toddler so he does not take a bus).  Originally our son was only supposed to be at school half days, but my husband just left him in school until 4pm each day (pick up is 11:30am) after about a month (we pay for each extra hour and it is fine with the school).  So my husband lived under the guise of "watching our son all day" as the reason he couldn't get anything done until I caught on.  My husband's original job was supposed to be remodeling our house (75% finished and he does have those skills) but he eventually became bored and moved onto something else.  I just moved out of my dining room and into an actual bedroom a month ago. (again rambling).    To an outsider, my husband looks like the stay-at-home dad who is taking care of the house and our son while I work, but in reality he sucks money, does no household work, does not want to get a regular job to contribute to the family, and barely cares for our son (an hour or two a day, cause he practically runs out of the house once I get home to "work" on his latest money making project and does not come inside until ~11pm or so). 

My questions are: How do you expect someone to leave who has nothing (his own fault) and is totally financially depended on you?  He is my son's father and I don't want to make him leave high and dry (he has maxed out all his credit cards), but I have NO money to give him because we live paycheck to paycheck due to his foolish spending.  Is is possible to do an in-house separation?  I am not dependent on him at all financially, but am not cold hearted.  Or should I just make him fend for his own and hope that he can figure it out?   

If anyone has had experience with being the breadwinner and making a spouse leave, please chime in.  Others are of course welcome.  This is such a sticky situation for me.