Just say, "Sorry for any misunderstanding, but my party is only for a few people and I didn't invite you. You didn't invite me to your party, so it's only fair." Or something like that.
Sounds like this is pretty entrenched! Make sure you are putting away any mementos that remind you of him. Also make certain that you have disconnected from his social media...
Either tell them that you can't do the sleepover on that date, or you could tell them that you aren't allowed to invite over everyone. If it's too late-notice, you...
Nerds sometimes have difficulty with social cues, so you should make your feelings clear. That being said, give him space, too. You'll want to be direct without appearing clingy. Also,...
It sounds like she was just jealous, so now she's trying to make you feel jealous as well. Try to gently remind her that it's okay for people to have...