So a couple of things stand out- The neighbor-you've told her you don't approve of the relationship right? While you can't control that, you can tell her that you won't listen to anything about the neighbor or conversations she's had with him. His opinions and insights mean absolutely nothing to you and if she brings up anything he says (especially about YOU) you won't listen. I think this is a legitimate boundary IMHO. He is nothing to you but the relationship is disrespectful to you and therefore you are not going to listen to anything about him at all.
So that is how you could address the questions. Now where to go? Honestly I struggle with this too. My instinct tells me to go out to a bar and get some action. With that out of the picture for now, other things just seem eh. Try the meet up app? Gym? Coffee? Call an old friend? Even if it's a movie leave well dressed and happy, come home happier.
