Hey my brothers in arms,

I wanted your opinions on how to handle a situation that I was recently confronted with. Just to inform all, I'm no natural alpha so here it is,

I saw a HB6 with really awesome clothes so, her fashion choice was amazing, like nails matched with cardigan (tiffany blue) and short rugged skirt. Anyway, I wasn't really going to hit on her but then thought, why not ask where she got such good taste from. Anyway we had a chat and intro kino, like shaking hands. Well her boyfriend apparently saw it. So we parted, and like five minutes later, up the hill, someone walking like a zombie from Walking Dead approached me and he's like "hey bro, I saw you talking to my girl, I wait here everyday and I see you talking to my girl" I'm like... shit is this guy drunk
anyway I'm like, "yeah,'
Jealous bf: "Why'd you talk to my girl? How long have you been talking to her for?"
Me: "I told her I really liked her fashion sense. You're lucky to have her. Calm down,"
JBF: "Its the alcohol, I'm a bit drunk." (I'm like oh shit and should tell you guys, he accelerated his car up the hill before, as I was walking up but I didn't think much of it previously.)
Me: "Yeah well, calm down." (slapping him lightly on the arm)
JBF: "How old are you?" (Anxiety overtook me)
Me: "17."
JBF: "17, finished uni" (LOL he was definitely drunk)
Me: "Haven't even started."
JBF: "So just a kid."
Me: "Yeah just a kid."
Him dancing around being drunk, pacing like a duck, walks away saying, "Alright, well don't talk to her."
Me: (Thinking) wtf why was I so scared.
I know its not a time to measure scrotal size and try to be alpha but I was really Beta. Before suggesting, bulk up and stand ground, how would you guys handle this type of confrontation and with confidence, without getting internal injuries. I ask cos this is the first time but probs wont be the last time, especially when i go out sarging again. Besides, being the wrong place to pick up a girl (which I wasn't really trying to), how would you find out if she's got an overjealous bf