Yitzchok, firstly, shalom uvracha! I went through a very similar transition as you, except I was coming from an MO high school setting, and not a hesder yeshiva.
What you’ll find in yeshivos is that when people learn, they are as the gemara says “they start out as enemies but end as beloved friends,” the passion and fire of milchamta shel Torah in no way is personal or indicative of a middos problem. As you saw, the bochenb was very nice to you before and after
But in learning, you’re going to have to be ruthless; not “to” other people, but “at” them, because you’re trying to figure out the emes, whether your svara is right or wrong, and that is forged only in the fire of rischa deoraysoh.
But the bonds you build with your chavrusos and members of your chabura/shiur are indescribable; I’m still close friends with chavrusos i had 17 years ago – Torah connects you on a level that’s deeper than anything else.