I started to triathlons. My initial goal was to get my strength back and lose some weight. But it ended up being so much more- having a goal i was working towards, trying to drop time and do better with each one. It was so import to do something for me. And gave me a life outside my kids.

Hmm, you didn't give us any interests to go off of, so a few random ideas- running, rock climbing, photography, pottery, gardening- even starting a community garden, volunteer at a local hospital/shelter/food bank, learn a new language and plan a trip 2 yrs from now to a country that speaks said language.

Other option- have her get a job where she works 1 or 2 nights a week and you do childcare. Brings money in and gets her out of the house.