An easy non-tomato pasta is a tin of soup as the sauce.

Butter and black pepper is as easy as it gets; get some fruit for afters and that's not a terrible meal. You can chuck in extra bits and pieces to make it more interesting (cold meats, salad veg, cheese, anything tasty you can get to bite size).

Corner stores have trouble keeping fresh produce in because it goes out of date so quick. It might be worth asking them if you could pick up any past their best items for cheap at the end of the day.

You can quarter an onion or a potato (no need to peel) and get through most soft veg with a butter knife. But you could do with a better knife. Ask around some charity shops, they'll often have stuff like that come in and (depending on where you are) many of them still function as both fundraiser and provider of cheap stuff for people who need it.

Good luck. Hope things get easier for you soon.