There are always people in life who will use you while you're there and discard you when their interest drifts away. That's not you being a fool, you just trusted someone unreliable, you were conveniently close and useful.
I've done the same. A friend I'd known and visited regularly for 42 years did the same, didn't tell me, I noticed it for ages on line, then 'sold'. The sale fell through. She is still there, I often wonder if she would have told me her new address.
We've now drifted but that's ok. I thought we had a strong friendship, I was totally unaware of any problems between us.
Coincidently I think my neighbour is soon to be selling up too. I know I won't be told as we aren't close, just polite. And that's fine.