Why does he keep doing this, He keeps calling me a B. I .T .C .H.?

ok so i've been dating my boyfriend for about a month, were both 16. for the past two days or so i've been ignoring him because he's been calling me a btch. he was " btch when u gonna let me fck" and he knows im keeping my virginity 'til im married. he said " btch why u ignoring me" and i said thats the reason right there you keep calling me a btch do i look like a animal to u and he started laughing then he texted me like 30 - 1hr later saying "why ignoring me btch?" and i said you know what btch im tired of your *** calling me a btch so im going to keep calling u a btch back. he said "btch fcck u too bad i dont care bout u no more, i hope u fcck a dude and he got aids. i hope u die btch". and some other stuff . i said from the looks of it u might already have aids the way you keep flirting with chicks ho. and if i did lose my virginity to you i probably wou;d have caught something btch. and he got mad and keep spamming my inbox so i deleted his number and deleted all hi messages he was sending withh out reading. so he told my associatete me "btches not sht but hos and tricks, too bad i pimp btches". when he was the one begging me to go out -.- . i could have told he was butt hurt when i blew up on him for calling me a female dog. but i want to know why he did that . . .