Not sure if it's a typo so just making sure your aware this is the Armoantic community (No romance). It's a really spelling mistake a lot of spellcheckers will make.
Also a note, I'm AroAce so I have the most shared experiences with your friend rather than you but I do take in a lot of information so I will try to help you out.
Firstly your feeling are valid always. The reasoning for the feelings maybe be not a great but feeling themselves should never be discounted. What may be happening here is your friend is discovering themselves and it's a very confusing time where you aren't sure what you are feeling and which type of attraction certain feelings are. It a confusing time and there are many types of Aro/Ace with Demi, Gray and Flux variations on both orientations. There is also the expectation to be in a relationship so you pretend till you can't pretend anymore, such as not wanting to ruin a friendship over something they don't/can't actually care about.
I don't know how your feeling and I'm not going to try and guess because there is very little I can relate to. I would explain to your friend that you want some space while you get over this but, if you do still want to be friends then day that. This is a complicated thing and maybe you could suggest just talking over text for now. It give both of you more time and space to think about what you want to say.
If they are AroAce they might not realise just how much it means to you and how hurt you are by their casual announcement. You may not be able to be mad at their choices but you can be annoyed at the way in which the news was delivered. I hope this helps and you are able to feel better about it at some point. If you want to chat more about it either comment or private message me. Best of luck to you.