In regards to that A-HOLE neighbor, as others have said, let the law know about him threatening to trespass and steal your gear. If they have record of that, they have something to go off of if your gear actually does come up missing. Getting a muddy or Lonewolf set is not a bad idea but I know when I was your age I didnt have the $ for that. Bottom line is you shouldn't have to worry about your gear getting stolen, especially on private ground.
As for the bad shot on the buck, I know you have had some bad history with this happening but as others have stated, don't let it make you want to stop hunting. All you are is a quitter and a loser if you give up after facing adversity. It is a not just a bow hunting lesson but a life lesson! You had the balls to go on this site and write about it, knowing that some guys were going to give you crap, so I know you have what it takes to get back in the stand and drill the next big buck that comes walking by. As Booner stated, focus on why you hunt rather than what you are going to kill. It is obvious you love deer hunting but I think you have let the desire to kill something with big antlers make you forget why you love deer hunting. One thing I do know, if you are not good enough and satisfied without a big deer on your wall, you will never be good enough and satisfied with it!...............The last thing; when you know you made a marginal shot, for the love of god, back out and give it at least 6 hours, if not more, depending on where you hit. We all know how bad you want to go after it but IMO that is something you know better than and totally Fed up on.