brotherdan, I had postpartum depression too, and the meetings actually made it worse! (surprise, surprise).
You could ask your wife if she needs you to pick up anything on the way home from work...then take your time picking up stuff on Thurs. Get home a bit late, and then get to the meeting late. Perhaps she'll hate being late and start skipping meetings the next time you're going to be late.
Point out how inconvenient it is to drag your kids there...it messes with their naps, bedtime, etc. It's not fair to expect them to sit still and be quiet.
Tell your wife how you're sad you don't get to spend much time with your kids. The meetings take lots of time away from parents spending quality time with their children. You work all day and only have a few hours to see them at night and on the weekends...you want to make the most of it.
Try telling her you need to work a bit late, but say you'll be home as soon as you can, and be just late enough to not have time to go.
Good luck! It takes time to break those habits. It took a few years for me to make inroads. I didn't realize what I was doing at the time, I just didn't like being at the meetings with all those phoney people.