I think you are being one. Here is why:
You are breaking out the "emergency" reason. How often does a real emergency happen, then divide that by a one in ninety chance that your neighbor will throw a party, and chances are those are pretty slim odds. When a reason has very slim odds of happening, it becomes a comical excuse. For example if a student fails to hand in his homework "because his cat ate it".
You are breaking out the good old "I said so" type of parental attitude. "Why dad?" "Because I said so". Yes you own the spot and yes you have technical power over this person. Yes a parent has that technical and mechanical power over a child.
But as they say, true power is not measured by your ability to slay with the sword but by your ability to grant mercy.
You had a chance to grant mercy here and you didn't take it. The past events might have annoyed you but this person only has a party every three months, some neighbors in town houses can have a lot of parties and be really awful.
I mean you live in a town house, not everything is going to be perfect.
They are not being perfect angels either. The fact that they take 10 minutes is asshole behavior on their end.
The issue here is that I think you are engaging in revenge type behavior, at incidents that happened three months ago for ten minutes, which can ruin the mood of every party they are having, every time they are having it, for them and the guests.
You don't know this person's life, the party might be a big deal for them, they might not have many pleasures or luxuries in life and they might work a lot, and that party is something very meaningful that they look forward to.
If you are arbitrarily spoiling the mood of the one party that happens every three months, then yeah maybe you are the jerk. Because really how many other opportunities are there to do something neighborly.
The greater damage is now that their neighbor thinks that you are crazy and vice versa, and you are going to walk past each other without saying anything.
People should feel comfortable around their neighbors.
Personally I would do something about it. You don't have to apologize for your stance but you should at least indicate to them that you are sorry that things had gotten out of hand.
Go ahead and be the better man, even buy a small gift that you think they will appreciate as a gesture. Even if they throw it in the trash.
Think of Home Improvement. Tim Allen's neighbor Wilson was his personal advisor allowing Tim to accomplish goal and overcome difficulties. But here you are, arbitrarily creating them during their infrequent parties. I dunno man.