I want to avoid my boyfriend so I am going to stay out extra late.
What is your reason for wanting to avoid your boyfriend?
He didn't take good care of me while I was sick.
It is normal to be upset that he didn't take care of you when you needed him but it is not good to try to get back at him. He could get really worried and start calling around getting other people worried.
Well, that's his fault. Guys don't care about those things.
Staying out late and not talking to your boyfriend is kind of petty and is only going to worry him. You are better off telling your boyfriend how you feel instead of being passive aggressive towards him.