Now I'd like to preface this by saying I dont defend this person's behaviour and his response was childish and wrong. I wish I could offer some advice and help on dealing with the social side of this situation, maybe all I would say is discuss it with the friend who knew him beforehand, maybe don't mention everything here about targeting but that his reaction and behaviour made you uncomfortable and it wasn't fun. That's the main aim of any consistent play group after all, to get a long and have fun. You never know, maybe a word from his friend will makw him realise he was being a salty dickhead and he'll apologise.

But social aspects and his behaviour aside, If you tell me this story without mentioning your gender I'd believe it 100% still. This guy is still an asshole, but it's entirely possible in EDH that someone would target the Baral player without saying anything, then get pissy and salty at a miriad of Counterspells. I know you mentioned he's playing much more powerful MTG cards, but Ive seen plenty people get mad a decks focussed around countermagic. And to top it off, decks like Mizzix, Baral, etc are generally known to be combo decks (reducing costs of instants and sorceries), the only way to win is kill them early by attacking them because if they establish a footing it's likely too late already. Its why I don't play Mizzix anymore, you either win, or lose horribly without doing anything first. It just isn't fun. I hope this maybe atleast makes it feel a little less like a personal attack against you, and that you might be able to share some salt stories with your fellow blue mages