Good lord not again....
I will tell you that as someone who has been pepper sprayed DIRECTLY, if you choose to use spray please practice it, remember that wind plays a very vital role in the use of pepper/bear/OC spray, if you have never felt the effects of it and then have to use it and take a good hit, you may be incapacitated, you will not be able to breathe, see, smell and possibly curl up like a little baby, ask me how i know!
I highly recommend you protect yourself, either via a personal sidearm, or spray. In either case practice, if you feel so inclined go ahead and spray yourself, you have no idea what it will do to you so you may as well know for sure that way if you do get hit you will be better prepared when it happens, that is why LEO's do it, not because its fun, we have to fight through it, if you have to use it you will likely have to fight through it also.
Bear spray is pretty much the only type of spray that compares to LEO strength and in actuality from what I know Bear spray is typically more powerful then LEO Strength OC, it effects different people differently, some can fight through it while others go full panic, check out youtube, plenty of comedy available. Practicing also allows you to know the range and spray/stream of the product you purchase, both would be important to you if you have to use it. As LEO OC is an intermediate weapon, non lethal, with our firearm the next level in force, if you decide to confront this animal, I highly recommend that you have a firearm in case you need to escalate the situation, better to have and not need then to need and not have, I do not believe you will need it but....
All of that being said, my first recommendation is to move, but I understand and agree that you should not have to because of your neighbors actions, but in reality, in your situation, that may be the best advice you have.
FYI, I stood in a cold shower for 40 minutes after I took my hit, holding my eyes wide open the entire time, I got out of the shower about 5 minutes into it and found out that gravity sucks, especially when you have just gotten OC'd, yeah the man parts....
Anyway I wish you luck and hope you got a laugh out of the last part of my post, it wasn't funny then but now it is LOL!