He got frustrated because he did not get the result he wanted---for your to just calm down.
But that is no reason for him to put you down or make you feel bad about how you are feeling or what you needed to talk about.
When my roommate/friend acts like that, now, I don't allow it. I go, "Bruce, I was venting, please don't get too technical; I need you to just try and see what I am going thru. If I can't give you the result you want, that's too bad. It's not personal. But I should be treated like a bad kid because I am not acting mature, rational, or enlightened."
But there were many years before I learned to stand up to him when he acted like that. I went thru similar to what you went thru---a lot of arguments, a lot of misunderstanding, where he put me down a lot, called me childish and emotional, etc. it hurt a lot.
Carol