Maybe its because he was autistic, but i left DS in night time pants until he was 7 or 8.
If your 6yo is still bed wetting, please save yourself the stress and put him back in night time pants.. it doesn't mean he SHOULD pee in them, have the same expectation that he get up and use the loo, but if he does wet himself, it saves the hassle of embarrassment for him and having to change pjs/sheets in the middle of the night.
I'm not saying its what you're doing at all, btw, but i dont get this obsession in insisting children who aren't consistently dry, not wearing pj-pants at night.
You need to ask the school to badger him about drinking during the day, i've had to do that with my DD as her flask was constantly coming home nearly full, then she was drinking nearly 2 full bottles between home and bed, and then up and down to the loo all night >.<
Other that that, don't feel bad, if you WERE a bad mum, you wouldn't be feeling awful right now. Things are so hard and you've a lot on your plate, and 11yo's are small assholes at times (i have one) and morning rule in our house is no tv/tablet/anything until you're dressed and ready for school!
Don't beat yourself up, give them a cuddle when they come home and if you feel you ought to apologise, then do, but also explain what they were doing to push you over the edge.. they need to know mom has limits!