Just Bought An Older Home In Ga. Neighbor Accosts My Wife Twice Now About Our Property Line.

Location: ITP Decatur, Georgia.

We bought an older home this summer. It has a few issues but we're just happy to be done renting. First day of owning the home about 2 months ago, our neighbor pops up and tells my wife that he has plans for his part of his property on our side of the fence and that he's been taking care of things(?) on this space and by law he's entitled to it. Scroll to bottom for lot diagram for more context.

Today he accosts her again and tells her he plans on putting a rain collection barrel on our side of the fence, taking down our fence, and planting fruit trees on the treeline that he claims is the property line because he's a homesteader lol. I have no idea how long this guy has lived here and what things he's been taking care of, I know of no claims or problems with property line from closing with homeowners ins, realtors, bank, or previous owners. He hasn't provided any documentation or survey report or anything. I have no idea if the previous owners had an arrangement with him but I am already frustrated with this bum waiting for me to be out of the house so he can confront my wife, who just wants to be happy in her new home.

I am trying to decide if I need to seek a lawyer for this, because at this point I want to tell him to stay out of my backyard but I have a feeling he's itching to escalate this. I was researching this type of stuff and I know not to do anything stupid like put new fence up or cut down trees or anything to upset the status quo until I have some facts. I don't even want to talk to him before I have a survey done so I don't come off as an asshole, especially if I'm wrong. I feel like the next step is to get a professional survey of the property lines done so I reached out to a reputable surveyor for a quote to hopefully put this to rest. Any other things to recommend would be greatly appreciated.

I have one main concern: his garage is actually on our property and I don't know if that helps me or hurts me, see this Lot diagram. Our fence connects to his garage wall and like 2 or 3 feet of his garage is inside our fence. I honestly didn't give one shit about it, I saw it said that's weird and that was the last I thought of it. I do not want to deal with any of this or have some escalating beef with a nut job neighbor that I haven't even met yet. Can someone please walk me through this, explain how this didn't come up in the sale of the house and what my worst case legal scenario might be?

Lot diagram