for the 1st time ever today

My boyfriend called me a bitch....
At 1st he said you're acting like a bitch then later said it again that "I'm being a bitch"
We've never name called when mad and he knows how strongly about I feel about NEVER name calling....(my ex would call me a bitch a cunt all sorts of stuff) so I made him very aware from beginning that I will not tolerate that type of verbal abuse. 
ANYWAYS. So today that happened....
I'm not sure what to do or what to say? 
We live together, in 7 months pregnant & we've been together almost 2 years 
Please help feeling very emotional about it 😞