Pees in my mouth ( BJ)

So I have been dating this guy for a several months. He never really had a good blowjob or cum with a blowjob so I wanted to be his little " "whore mouth " and I was able to make him cum in less than 10mins and I swallow his cum. Everything was good did it 3 more times he came etc.. So I went down on him again and this time he peed in my mouth. I gag and spit it out obviously he apologize and we tried again and again and keeps peeing he claims " his.body relaxes so much with me that he just pees " . Any advice????????