<human>: Could you distill the essence of the text into 1-3 sentences?

I (m, 23) just lost my girlfriend (f, 22) to her best friend (m, 20), that I share a mutual hate with.

My girlfriend and I had a bit of a disagreement yesterday morning, a slight argument, and honestly I don't even remember what it was about. I think it was something about us trying to decide a movie to go see. I don't know, I just remember it was something stupid that we'd usually never fight about because I usually just let her have her way with stuff.

Anyway, last night, she went out and about twenty minutes later her best friend comes over to my house acting really pissed. He said she showed up by him crying and saying I was being mean to her and making her feel like shit (when I hadn't said anything mean to her because I feel seriously bad if she even seems upset at me, but whatever), and he starts yelling in my face calling me names, so I tell him to fuck off.

He punches me. I punch him. After 5-10 minutes, we're both laying outside in the lawn, bloody, in and out of consciousness and my neighbor called an ambulance for us.

Later at the hospital, just as I'm starting to really wake up and be aware, I notice my girlfriend walking past my "area", and I try to call out to her, but my throat was a little sore because I was just waking up. I get up and limp my way over to see her walking into the space next to mine, and say something, so pull the curtain open to see the other side and she's making out with her fucking friend, notices me, says "you're a fucking piece of shit, look what you did", and goes right back to kissing him. I think they're making out right now on the other side of the curtain.

I was in love with her, planning on proposing next week.
<bot>: I was in love with a girl who sicced her best friend on me. I got put in the hospital because of her, then saw her kissing the person who put me there.