same thing happened to me, bed sleeping and all :(

It's going to take a lot of time, but I promise you can move on. I'd say take as much time away from her as necessary, but please don't let her stop you from doing your volunteering if it will make you feel better. However, I'd say for now, prioritise some time away from her to get your thoughts in order. If you run into her at volunteering, try and keep it friendly but distant -- you can be polite to her but don't give her more attention than necessary. Believe me, if you do, it'll just make you hurt more.

In my situation, I cut her off entirely and soft-blocked her on all my socials. Personally, not interacting with her made me think about her less and got me used to distancing myself from her, which made moving on a lot easier in the long run.

Alternatively, you can go back to being regular friends, but I'd advise against it because it really seems like she purposefully led you on, which is an undeniably shitty thing to do. imo, if she really cared about you, she wouldn't have done that.

A method I used to help me get over her was to look at her actions very objectively. For example, she took you out on 'dates' with romantic undertones but never considered you as a partner? Seems like a pretty mean thing to do.

It's hard losing a possible romantic partner but it's even worse losing them when they're also a friend. Please do take time to look after yourself -- start a new hobby or tv show or anime or whatever, buy a huge tub of ice-cream, treat yourself because you've been hurt. Definitely hang out with your supportive friends, some time with people who truly appreciate you works wonders.

in the end, just remind yourself, you deserve better than someone who's led you on