Is my boyfriend a douchebag?

Hey ladies, I need your opinion. Yesterday, I was with my bf at his house with his friends, when one of his friends told us that the girl he has been talking to was on heir way to hang out with us. I was excited to meet her but my bf kept telling me that she did not like him, I was like “have you met her before?” He goes “a few days ago she came” to what I asked what happened? Why did she not like him. To my surprise, he processed to tell me that first night she went to the house, he (my bf) smacked her in the ass as a joke to give his friend like the thumbs up (I guess) obviously she did not like that, and he apologised instantly (yeah he was drunk).

I am not only embarrassed of his actions but embarrassed to find out that I am dating someone like that. I don’t know if I am overreacting or what but how disrespectful is that??

What are you guys’ thoughts

Thanks!