That is an excellent question and I can relate to what you are feeling. When I first started learning to play guitar and sing I got to a point where I was perfectly comfortable home alone on my couch singing and playing for the furniture. But bring an audience of even one person in the room and all of a sudden I couldn't get my fingers to work and could not even play a basic chord! It sounds like you are experiencing the same "stage fright" that I endured for a time. Even though nobody is sitting in front of you, you perceive that they are listening and the fact that one of your neighbors commented on your playing confirms that in your mind.
The good news is those feelings are perfectly normal for most humans. And almost everyone eventually learns to overcome this natural phenomenon. Once you overcome this self conscious fear of being judged, you will relish every opportunity to perform for others (live). Sharing your music with others and playing with other musicians will take your enjoyment of playing your instrument to a whole new level and you will become even more passionate than you are now.
I am sure you set goals for yourself in terms of improving your guitar skills. It takes deliberate work and practice to achieve each of these goals. Nothing comes automatically in the beginning, but the more you practice, the more automatic many aspects of your playing become.
Make it a goal to develop your confidence (along with your playing skills) to a point where you become not only comfortable playing for an audience, but seek out opportunities to share your music with others. Consider what steps you might take towards accomplishing that goal.
One obvious first step might be get to a point where you can play loud enough for your neighbors to hear you. You might start by playing some songs you are very comfortable playing, such as the Radiohead song you have already received positive feedback on. What other songs can you play as well as you play that song?
Practice particular songs over and over either using a very thin pick, finger picking, or an electric guitar with a headphone amp. Once you have 3 that you feel you can play with some level of competence, make that your first "set list". Then conduct a performance for your unseen "audience" (neighbors behind the walls) by playing your three song set as you normally would if you were sitting in a cabin in the woods all alone. Consider this an exercise towards accomplishing a goal. Continue to build on your initial "set list" adding new songs regularly and extending the length of your "concerts".
Eventually you will become comfortable enough to take the next step towards your goal of loving to perform live and invite a friend over to listen to your performance. Bolstered by the inevitable positive feedback your next step will be a group of friends, eventually working up to performing a 15 minute set at an open mic.
Always keep this in mind - you play better already than almost every one of your neighbors because they don't play an instrument at all. You will find that many folks will admire the fact that you can play even a basic three chord strumming song because most folks can't even play a C chord much less put three chords together with the proper rhythm and timing. You are able to do something that very few if any of your neighbors can do. They will be envious of your ability, regardless of your current skill level.
Overcoming "stage fright" is a normal part of your evolution as a musician. Like every other skill you develop as you progress on your instrument, it will be a deliberate process and take work. But the enjoyment you will derive from sharing your music with someone other than yourself will make it worth the effort.
Good luck and enjoy the journey.