Heather's stress

I'm continuing to do what I can to move this divorce forward.  I didn't want the divorce, but at this point, I want to move on with my life.  We are planning on selling the house "in the spring" but Heather hasn't done anything to make this happen.  I interviewed four contractors to get the house fixed up.  I've been running around looking at paint colors and trying to find matches for our broken tiles.  I started the contractor work this week of repainting the kitchen into more modern colors.  I see progress toward moving forward and this makes me feel alittle better.  I still have sadness that the house we built is having to be sold, and some stress and anxiety about it, but I feel good that there is progress.
Heather seems to have the opposite effect.  Her stress level has gone up tenfold over the past few weeks.  She's working all kinds of house and all weekends.  I'm finding myself doing all the laundry and all the house work as she locks herself in the bedroom and works on school work.  I don't mind.  I feel like I'm learning to live for myself.  I do mind when I work on cleaning stuff all day and then she criticizes the way I've done it.
She says that some of her stress is from her new job and some is from seeing the house getting ready to be sold.  Her stress has been so bad it's causing migranes and she's goign to bed at 8:30 the last three days.  She gets stressed and then she starts yelling at the kids and yelling at me.  I'll pull the kids away from her, indirectly, and I'll walk away from her when she start yelling at me.  Later, she will apologize and say it's because of the stress.  The next morning, she's yelling again. 
I'm starting to wonder how she's really going to be able to handle things once we both move out.  I'm preparing myself to have a house where I can support the kids full time, if I have to. 
I want to be compassionate toward her and help her out.  I know, however, that she blames me for what's going on.  Her perceived failures of me as a husband have never be forgiven and she sees me as the source of all the stress and hardship she's going through.  When I try to be compassionate, she often blows me off, or accepts some small portion of my help, but then bites my head off a few hours later.  I've got a thick skin, but I'm growing tired of that.
She's the one that asked for the divorce and I've come to realize that she had checked out of the marriage months before she asked me.  However, now that the divorce is becoming more of a reality, I think I'm more prepared than she is.  But this is the world she built.