Hugs to you.
I'm going to repeat some things from an earlier post and make a suggestion or two. You are giving this woman tremendous power over yourself. I'm reading a great deal of anxiety and fear in your posts, caused by what this woman says. The comments about the new car making you "better than us," seems to have cut very deeply. Reacting that strongly to a stupid comment isn't good for you. Living in fear that your neighbor might send you a text message is not good for you. I strongly suggest that you spend some time in introspection to understand why you've given her this power. I further suggest that you spend some time with a professional to do this. (Hint: I find the fact that you have emphasized that the car was "new to me" -- that is, used -- to us, strangers on the 'net very interesting. There's nothing shameful at all about owning a brand-new car. Why are you afraid that she (and we) would think the less of you because it was brand new?)
Have the confidence that you are a good person, and are entitled to the things you have and the life you lead. Understand that what she says is nothing but words, and words that say a lot about her and nothing about you.
Be The Cat.
Final advice: I'd ignore her. In trying to stop persistent behavior, you have to be absolutely consistent. She wants attention/a response/to control you. If you respond, you're giving her permission to continue. She will continue for a time, even if you don't respond, but responding will just prolong the bad stuff. Like pulling off a band-aid, it's best to get it done quickly, albeit painfully, than to drag the pain out for a long time.