Re: How to make it on your own?
Eventually she will need to get some type of job. She could try for something she can do while she has the kids (e.g. babysitting) but if her DH knows she has money coming it chances are that he'll expect it to go to the household and not for her to be saving it. That could cause problems itself.
I would advise your friend to contact a woman's shelter in the area. They are experienced and can give you friend advice. Applying for state aid may help her a lot. She may be able to get assistance with finding somewhere to live and rental assistance, and even money to pay for childcare while she works and/or is in school. Also, she may end up getting child support since generally when someone files for aid, they go after the NCP (non-custodial parent) for CS.
Like a PP said, it may be easier for her to move out rather than to try to hold onto the house. She may find a cheap place to rent (or get housing assitance) and then what happens with the house may become a part of the divorce, as well as the division of the other debts.
She can also see if there is Legal Aid in your area which can help her with filing for a divorce and custody of the kids. If there isn't, usually it's just forms and she can fill them out herself. Although, the clerks often can't give advice, they can tell you what other forms you need to do this or that.