I'm in NY at the final boss that will end this NY expansion and ive been trying to kill him for the pass week and I gave up. Guns not that powerful and he has all those gadgets killing me. I want to play with my friends again and who are not buying the NY expansion. I tried joining their game but it's not letting me. Am I really stuck here till i kill this guy?
Yes, indeed. At least with this character. You need to finish the narrative content of the DLC in order to be able to return to DC as a level 40 agent. At least with this character. You could still boost a new character to level 30 and use this character to play with your friends in DC.
Or try to matchmake for the final Keener-mission. Or maybe send a call for help, you get downed. There are a lot of friendly agents out there, that are willing to help!
Good luck, agent!