Fish: another thought would be to "drive" partway there and then bike commute the rest of the way in - if there's a safe place to leave your car all day. Don't know what your work schedule is like but (when I deem the weather is warmer) I ride on my lunchbreak. I get an hour for lunch so I can get at least a 45 min ride in with the extra 15 min for changing and freshening up. Would that be doable for you??

Also: does your DH ride?? If you could get him involved you could get trailers and ride with your DH And your kids - then you don't have to feel guilty or leave anyone at home.