i got carried away

hey guys so i have this thing where i take care of my best friend since childhood but like in a weird not-sexual kind of way i know it's weird and i'm sorry if this is tmi but she kinda looks up to me as more than just a friend sometimes. we're both 28 but she likes to pretend to be younger or something so that makes it all very confusing for me. so yesterday we were at my place watching a movie, and suddenly out of nowhere i felt this urge to just wrap her in a blanket and tell her everything would be okay like mom does. next thing i know, i've called her baby and she's giggling like she used to when we were kids. it was totally innocent at first but then i started making her sit on my lap like a little girl and before either of us knew it i had this hand in her hair pulling her head down to whisper some kinda bullshit about being good for me or something. she stopped giggling, looked up at me with those big eyes that never fail to melt my heart, and just said 'please no daddy.' and suddenly there was a whole lot of tension in the room i'd never noticed before. we both sat there not talking for what felt like forever but was probably only five minutes max. then she got up, whispered sorry about everything somehow ruining our friendship or something and left. i've been stuck here wondering if i should go to her place and apologize or just leave things be because this was my fault. i don't want to lose her but also i know i overstepped big time with that weird pretend parent thing we got into. sorry for dumping all this on you guys i really dont know how else to deal with it. thanks in advance.