Your partner selling you out at the pregame was a bad move on his part. I worked with veteran officials who were jerks when I was a newbie too as I am sure we all have. The guy who comes in for your freshman game and lets you know what a big favor he is doing someone by working such a low level game because hey, he has done college games. Then he tells you all about how great he is.
I hope to God I never become that guy. I will say that 95% of the officials I have ever worked with were great people who tried to help me when I was less experienced.
I didn't start officiating until I was 39 so stick with it. It does get better and so will you. I don't think I could have done it when I was 18 because I was probably too much of a hothead. The maturity of the additional years is a good thing for me. As you get more comfortable with yourself on the court, the criticism from the coaches will bother you less and you won't take it as personally. You will also become more comfortable dealing with them. Don't be afraid to give out a T, it is just another violation. Don't make it personal, it's just one call out of many you might make during a game. I honestly don't even hear coaches or the fans most of the time anymore. Good luck and hang in there.