Just punch her in the throat.

Wow. That's so mature of her. :/

If she thought it was a gift FROM YOU, why did she ask YOUR opinion on it?

I woulda popped that bitch like BAM NIGGUH now who da boss

You don't even have to wait. It is yours, not hers. Take it back. Easy. Stupid people are like animals, you have to be a bit firm sometimes or they will just run amuck.

I agree with everyone else. It's yours, not hers - take it back and store it elsewhere. Also, did you do anything else? Try to reason with her, take it back, call the cops? I'd like an update to know if you got your property back and if you managed to work through it or not. It'd be great to know if you got your piece of work back.

Sign the artwork when she's not at home so you have proof of your rights to that painting. If you let her get away with this then she'll try to get away with more and that won't be fun. Do you want the problem to get worse? Don't let her get away with taking your painting. She can't say it's a "gift" if you didn't actually give it to her and told her to keep it.

Since it's yours, and you never gave it to her, by law she stole it. Tell her that and if she doesn't give it back, either take it back or go to the police.

that's really rude. I know how that kind of bull feels. Honestly hurts but it's yours. if you have a signature on it, then just take it back. no one should take stuff without being said.

report her for theft.