Is the new player *that* guy?

Not sure if it really is a horror story, but for me it's slowly getting there.

I joined an ongoing campaign about half a year ago, because they had only two players left. The DM is a player of my own long-term campaign so I thought 'sure'.

I always thought I didn't like playing D&D as much as DMing, but I actually had a blast! But we were still only 3 people. So one of the other players proposed a friend to join after about 10 sessions.

He was completely new to the game and I thought he had a bit of a strange attitude. Especially toward my character, he seemed pretty hostile - but we were the only ones that had no connection with each other (because we didn't share the acquaintance the others shared). No problem, I thought, he is new.

We proceeded to banter a bit, but his comments seemed barbed to me. Well, we talked a bit after the session and we have really similiar interests, he is nice and all, so all good.

Then we get to the final dungeon of the campaign and the DM presents us with a child that might be an agent of the enemy (the BBEG replaces people with mind controlled machines). Everyone says we can't kill the child, but he is adamant on discussing it. When he didn't let it go, I veto'd it because I do not want to play something like this, it's a red flag for me. But he seemed pretty annoyed and didn't say much after that.

We talked about it the next session and he said pretty much nothing to that. Only that he'd let it got. Alright then.

Next session we encountered an NPC that had fled the BBEG after being mind-controlled by her, but helping us she was taken again. We all wanted to save the NPC and didn't attack her. She attacked us - but not the new player. He still attacked her when she teleported through the room, despite the NPC doing nothing hostile toward him. I found that pretty annoying, though we managed to break the mind control. I just ignored him.

Today, in the dungeon, we discovered a teleportation circle - a player proposed to send my character's familiar through. The new player doubled down on that. The familiar is really important to my character, and so I roleplayed it (he's a squirrel) to fluff up before him and climb up his leg to whirl all over him - explicitely not to harm him, but to annoy him a bit. He took his mage hand, rolled really high, and grabbed the squirrel. He threatened to throw it in the teleportation circle if he didn't receive an apology. And he reacted pretty hostile as a player, not even only as a character (even though I think this would have been too much already).

We beefed over that, because he thought he hadn't said anything about throwing the squirrel in the circle. I asked him even if that's true, why did he have to escalate every situation and act against the group? He explained and I partly understood his character motivations, but it's annoying as hell from a meta perspective nonetheless.

I know I could have avoided that last situation, but it was meant as a funny scene, not a hostile or even a provoking interaction. I’m slowly losing interest in this game with a conflict in every session and a player that treats every interaction as a provocation toward him. Am I overreacting? Or is someone like this just a nuisance?