What does this mean 😭

Backstory me and this guy have been coworkers since August till he left in September/October

and we remained friends

and there’s always been some weird sexual / romantic tension there but like he NEVER made any moves so i just figured it was in my head until i found out he was dating some girl that lives far away

And they’ve been together like 4 years or some shit but he still would like act flirty towards me

and Today after nearly 10 months of this weird friendship he fucking says THIS

like ok?? lol. then why aren’t you single if that’s how you feel?

what do i even say?? ik id be pissed if i was his gf. i’ve never made any moves on him bc i know he had a gf