Just how bad is it to call a girl a bitch?

So I was at a kickback last night and this girl I know says hi to me and started hitting me like really hard she's a small girl so it didn't hurt or anything and I kind of just shrugged it off and I didn't really say anything to her but then later I went for some water and she pretty much karate chopped the middle of my Adams apple several times to which I replied "aye wtf bitch" and she got extremely but hurt from it and said what the hell don't call me a bitch and I had no idea what to say cuz it just kind of slipped and I didn't realize until after I said it. Then I kind of just left the house awkwardly and she didn't say bye to me when I told her bye lol. So is it pretty much over with this girl or is there hope?
Just how bad is it to call a girl a bitch?
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