He'll get over it or he won't. If he won't - - especially to the point of making you fear a temper outburst - - he's not the sort of person you should be working for any longer than you have to. It sounds like the other shop has so many positives going for it that you would be doing yourself a disservice to pass up the opportunity. That maybe should be your overriding consideration in weighing a switch.

Keep it in perspective of going to school. As I told my kids when they were in college: college student is your number one and primary 'job' right now. That is what is most going to shape the rest of your life. EVERYTHING you do should complement that mission and goal. Decide which one of those shop jobs best supports that goal and come down on the side of that. If that means leaving your current boss and he cannot accept it from that standpoint that is his problem and definitely not yours.