I don't know what to do with my friend who's always jealous and sometimes a bit btchy

If you want to be nice, find out her favourite soup, makes a batch and take it to her. Sit with her over a cup of tea, coffee or shared soup, and ask her how she's going with her illness and getting better.
At some point, tell her you can't afford to pay for both your meals and you want her to pay for hers from now on.
Adopt a rule of never giving beyond what you can afford in time, energy, resources and money. If they ask for more than you can afford, say, "No, I'm sorry but I just can't stretch that far."
This is called having good boundaries. It protects you against users. Some might fall away when they can't get everything they want out of you - but if they do that's a good thing.

Good friendships are built on equality, honesty, respect, trust, responsibility and good will.
If either can't measure up to those basics, the relationship will not survive in the long run.

How do you know she is jealous of you? Has she said so?
What, specifically, does she feel jealous of?
Jealousy can be one of the most destructive emotions. If she really does feel that way, it would probably be best to drop the friendship and
be open to other friendships with people who don't have such mean personalities.
A good friend wishes the best for their friends, is happy when they're going well and rejoices when they have successes.

[c=800000]1. If you go to lunch together, when the waitress asks how many checks be sure to say, "Separate ones."
2. If you offer to help and she asks for too much, say "I am sorry, but this is the best I am able to do." [/c]

U need to set boundaries for mutual respect and happiness. If neither one obliges to these boundaries then its not gonna work out.

Boundaries. It's okay to set them and enforce them.

She sounds like a user 🫤

Fuck her man its the only way to fix this

Let her go