I'm going to break up with my high school sweetheart but let her keep doing girlfriend things for me
I'm not sure I follow, why is that and what 'Girlfriend Things'?
She's not really doing it for me, she is just being someone who wanted to be in a relationship with me.
It's okay if you don't want a relationship. But I don't think this is being done for the right reasons.
She took advantage of me, so it is fair I do the same to her.
You shouldn't do this. Neither of you seems to actually, genuinely like each other. Better to just make a clean break from each other.