I went to my neighbor's place to see what would happen if I ender pearl into his blocked nether portal, I got stuck in it and I can't chat because nether portals don't allow anything
Do a Ctrl+Alt+Delete to open up task manager. From there you can close minecraft, so you can go on some other server. Otherwise, a staff member should tp you out.
You need a senior staff member's help, so PM them. But before that see if you can get your friend to break the portal for you.