I [16M] continued to engage with [17F] the person i liked, even though they were in a relationship

I [16M] continued to engage with [17F] the person i liked, even though they were in a relationship. I kept trying to adhere to my morals, tried to say it wasn't right, i felt guilty then, and i do now. I dont know why i caved in and kept talking to them, we've liked each other for a while now, she was in a bad spot mentally and i feared if i kept stating my boundaries she'd start spiraling and getting worse. So i kept talking, and we ended up talking more, i was comforting her, holding and hugging her, but i feel so wrong for it, because it wasn't just platonic, i knew what i was doing, and i felt paralyzed before and i didn't like it but i kept going along with it. I feel like a shitty person, everyone will hate me more than they already do, i just wanted to be a good person, and i caved in and continued talking to this girl that i've been crushing on for a while now. I want to cry thinking about how hurt the other person would be, knowing how close we were talking, i wish she could have just broken up before, why did i let myself do something i kept telling myself i didn't want, feeling every cell in my body being paralyzed with not knowing what to do, i just wanted to run away, and i did something so horrible i cant erase, because i couldn't run away. My best friend would hate me for it, and everyone else i know would too. I hate myself for it too, and i dont know how to live with it, because all i want is to be a good person.