The LBS generally goes through the "LBS diet" of being unable to eat and loosing plenty of weight. I've not heard about a WAS gaining weight, although the disrupted lifestyle certainly could lead to poor food choices. And, it is often described that the WAS can look "in rough shape". Good that you noticed that it is possibly due to her own stresses.
Unless you are going dark and if your "as if" is in good shape (along with your detaching), then it should be OK for her to help you with painting.
If you know when you are going to paint (not based on her availability; strictly on what you planned, without the knowledge that she said she'd help_, then certainly you can let her know when you plan on painting.
Just make sure that you DON'T EXPECT her to join you when you paint. She may appear to be really excited to help, and still not show.
What ever her reasons, even if it simply is "something to do" for her, is really irrelevant. Every opportunity to have a pleasant or comfortable interaction is an opportunity for them to question if things really were that bad, or that things could potentially be different and better, if there is a R.
