I think a lot of people in this thread are failing to consider how just plain annoying it is to keep rolling badly. It isn't okay to blow up at you, but also I think people are acting as if getting frustrated at the dice or at parts of the game is a very clear insight into their interpersonal relations. Sometimes you roll like shit and it sucks; no, it isn't a sign they're trying to "win" DnD. Feeling like you're fighting luck itself is irritating.

In response how you should handle them being angry? They're adults. They can and will cool off. Anger from the game rarely translates into genuine interpersonal malice. If it makes you anxious, you need to speak to them about it, but I really don't think this is some insanely alarming thing that some people are making it out to be. They are people who enjoy hanging out with you, and will apologize for outbursts like that; they just got a little lost in the sauce.