It seems like you have maturely recognized that this is an unhealthy relationship, and your continued participation in it and taking care of her isn’t helping her learn to take care of herself and put in the work to make a change in her life for the better.

However, I don’t think continuing to be nice and a good boyfriend and then abruptly breaking up with her when she gets home is a good idea. I think you should talk to her and tell her everything that you’re feeling about the relationship. Tell her you’re unhappy, tell her you’ve been bottling your feelings. Then when you do break up with her, at the time that feels right to you, she won’t be left not understanding why.

There is nothing worse than a breakup that you don’t understand - especially when the other person doesn’t contact you for a long time afterwards.