For context, I (M24) have a very good friend (M26) who is in the Army and has been for 4 years now. About 6 months ago he introduced me to his new girlfriend(F27) while he was on a leave. He did so by asking if I could take him, and her on a trail ride. (I own horses). He told me she was a horse expert, so I kinda put her through the ringer that day as any good friend would, and her whole attitude was very "better than thou". Even going as far as to criticize the way I stack hay in my own barn. But whatever, horse people can be snooty, I get that, and she was nice otherwise and grateful for the ride. He told me that day, that it was their first official date.

Later on I learned that they had actually known each other as friends for about 3 years. I found this odd because I'm definitely his BEST friend and I feel like I would've known about this if they were actually friends. Fast forward 4ish months (about 1 month ago) and I get a text from him asking if "I am ready to be a best man?" Confused I ask him to explain, and he claims that he is gonna ask her to marry him. So he does about 1 week ago and she says yes. He calls me and texts me happily saying he can't wait to have me as his best man. Now here comes my reasoning

1. He was engaged previously to a woman. The engagement was broken off because they didn't know each other well enough and things got too messy. I was there for the whole thing and by his side with support for all the heartbreak and pain. I don't want to see him get hurt again!
2. He is a very intense human being. He doesn't jog, he runs. He doesn't hop, he leaps. And he doesn't like...he loves. But this means he has a bad habit of getting swept away by the honeymoon stage of a new relationship. I fear this is what he has done.
3. Marriage is A GIANT step in any relationship and soooo many things have to be known about the other person before you should commit to being with someone FOR-E-VER. Many of these things I feel like he does not know about this woman because he's got heart eyes and they have only been dating for <6 months!
4. I am a full time college student and work full time. Between my limited time and even more limited money, how on earth am I supposed to be the best man at his wedding. There is a ton to do with that responsibility, and I'm not sure if I can logistically handle it all.

I recently told him all of my concerns and everything I was thinking, followed by telling him I would support him no matter what. Now he has not answered me and won't return my calls. I know he's pissed. AITA?

*Edit: this is my first post on here, I've seen about a dozen comments, and I'm just gonna say, I think I'm really going to enjoy this sub.

*Edit #2: I will not say another word voicing my opinion on this matter moving forward, unless he brings it up. Not trying to change his mind, I just thought he should know once what I thought