Thanks everyone for the replies.
Yes, chickens are allowed here, up to 75. (But we only have four.)
No, I never agreed to babysit for her. They both work long hours, and when the kid gets locked out, her mom would tell her to come here. Without asking us. I couldn't leave an 11 year old girl out in the cold. But I guess if it happens again, I'll have to say no. Poor kid. Her parents are never around for her.
Yes, I guess you're all correct that I should not have gotten rid of the composter. But it's just my personality type to try to get along. I hate conflict. I want people to like me! But you're right, that can't always happen.
I just walked over to the other neighbors to see if any of them had problems with the chickens. They all said they enjoyed watching them. (One of them said, "oh, the b---- next door doesn't like the skunk smell?? That's my dog. Hm. Now I'm so glad she got sprayed!"
Anyway... I'll try to stick to my guns from now on. And just stop answering her phone calls. It's so stressful... but your posts sort of solidified my thought that there's nothing I can do to make her happy.