My mate is going out with this lad....?

my mate is going out with this lad who is leaving school. the only problem is i used to like him but i dont care that they are going out. now he keeps saying to her wow beckys hot (thats me) and i have seen some of the texts he writes to her and most of them talk about me. he always flirts with me and i feel really bad. i dont want to loose my mate