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

I've been friends with John since September. We've never had any disagreements except for once when he got in a fight with one of our mutual friends and we haven't been as close since because I've remained friends with that mutual friend. So here comes Katherine. She's a mutual friend of us both, and I've had feelings for her for a while I've only ever felt this way about 2 other people. John is a naive guy, he's never been in a relationship before. So turns out that things seem to work out for me for once. Katherine and I both have feelings for each other, I get to be happy for all of two seconds. 

Turns out John likes Katherine too. Now Katherine and I have just barely let on to our friends that we're now a "thing". There's no PDA or any of that. But John starts ignoring me/not inviting me to things, so I confront him. He basically tells me that he can't deal with Katherine and I being together and it seems like he's asking me to break it off with her. So, I ask him if he is asking me to break it off with her. He says "yes". According to my values my loyalty to my friends transcends anything else. I tell him if he's sure, because after this we won't be friends anymore. He is. So I break it off with Katherine. There's a lot of crying she doesn't understand why I have to break it off, and to tell the truth, I don't really get it either. I have only been this depressed once before, and I nearly offed myself then. Did I make the right choice?
<bot>: My friend asked me to break it off with a girl I have strong feelings for. I did it, and now I'm regretting my decision as I'm very depressed. Did I do the right thing?