How to tell my roommate I'm moving out?

I’m currently a junior, living in a double with somebody I was placed randomly with. She’s very nice, but very hard to live with- she plays loud music, rarely leaves the room, has a lot of clutter, etc. Furthermore, this is my first semester back after taking a leave to deal with an eating disorder and she sometimes makes comments about what I’m eating, and I get really uncomfortable eating in front of her. plus, in general I can get very anxious and often need to be alone just to decompress, but like I said, she doesn’t leave much.
All this being said, the counselor at my school put in an accommodation order saying from now, I get priority for a single room. I SHOULD get a single room offer for next semester, but won’t officially get an email with the room assignment and building until after Christmas. I’m hoping the single will be in my current building (which is where all my friends and most juniors live), but it could be in a building thats far from most others in the school and is mainly girls in their sophomore year. Anyways, I’m a little undecided about if I’d be comfortable moving to that different building, but I know ultimately my mental health would benefit from it. I can’t keep feeling so uncomfortable in my own room.
How do I tell my roommate I’m moving out? I’m leaving for break early tomorrow morning, so should I tell her tonight? Or should I text her over break after I know FOR SURE what my room is (even though no matter what the school has to offer me a single somewhere)? Or should I wait till school starts when I’m all moved out and just say “oh yeah, I moved out?”
I just don’t know what to do! I want to stay on good terms, especially since we have many friends in common. Any advice is appreciated.

Definitely do not spring it on her and say oh yeah I moved out. She will be hurt and confused and assume she did something wrong. Tell her as soon as it’s confirmed, and that you really enjoyed living with her but for personal reasons, you need a single. If you want to remain on good terms, tell her you’d like to still meet up for lunch or whatever.

I wouldn’t mention it until you have confirmation of a single, in case the single doesn’t pan out for some reason.

@rebeccar @doschicos so do you think a text over break is okay versus in person?

I would say you’re on a waiting list for a single and you may be moving out in the spring should one become available. and imo in person is always preferable to text.

I would even take it back a notch to “my counsellor recommended I get a single for next semester so got me on the waiting list but I want to stay friends” or something like that. Assuming she knows you go to counseling, of course. It would be kind of awful for her to come back to a surprise new roommate with no heads up, which could happen. This also gives her the chance to get her own new roommate, maybe from one of your mutual friends who also wants move. There are two of you in this living situation, an two of you will be affected by the change. It’s only fair to give her a heads up about it.

If you are fairly certain you will get a single, I do think elliebham and red poodle’s advice is good advice. I wouldn’t want to raise the issue and then have to live with that person for another semester if things fall through but if it is likely to happen, an in person heads up and an explanation that it is about your needs rather than getting into what she lacks in being a good roommate sounds like a considerate course of action.