What a $!#!
I remember being put down like that in front of my children & it's not nice.
Maybe next time there's a school project (I just had a solar system & a rocket one from both daughters at same time) he can put the time into his children & work through it with them from stratch to finish, then anything that causes problems would be up to him to sort out & you'd have nothing to do with it.
Realistically I know he wouldn't put the time in.
You're a great Mum & don't you forget it.
Hugs.