[MF] I (M21) fucked my friend (F23) after a break up

Hello, this is my first post here and it’s a bit of a long one, so if you wanna skip to the sex part just look for the (). Feedback on this story is really appreciated tho lol
For the people who read it entirely, you’ll know how confused I am about all this.

So first and foremost, I gotta say two things: 1- English is not my native language (sorry for any misspellings), 2- this wasn’t in any way planned.

This friend of mine was going steady with this guy for about a year and a half now, they were already living together and having generally a good time besides minor setbacks. Then all of sudden BOOM, everything came crushing down! Her boyfriend was in the army, and apparently when he traveled for duty he fucked a bunch of strangers with the confidence they’d never seen him again. A friend of his from the military spilled the beans to his girlfriend and she had a meltdown.
Someway, somehow she had chosen me for comfort. Texted me in the morning asking if she could come over to vent for a little bit. I never ever considered we could end up doing something besides talking, because even though I had a gigantic crush on her, when we met I was dating at the time so she was always respectful and wouldn’t flirt with me or give any signs of interest.