xxx@hotmail.com is not an Apple ID

What has happened is that your brother, instead of signing out of your account and creating a new Apple ID and iCloud account for himself, has changed the email address which forms your Apple ID. The first thing he needs to do is to sign out of your account and create his own, otherwise you are heading for problems from which it will be difficult to extricate yourselves.

As to your ID, it's now whatever he changed it to. iforgot.apple.com is intended for people who have forgotten their password, and it doesn't tell them the password but issues them with a new one.

Once you have got your brother out of your hair, so to speak, you need to sign in at http://appleid.apple.com using the ID and password he set up. Then you can click 'edit' next to the ID to change it to something else. I don't know whether there is a delay which would prevent you from using the old ID for a period of time - it's very likely - if so you will simply have to use another address to form the ID.

I imagine this is the delay I spoke about above. I'm afraid you will not be able to use the hotmail address, at least for the time being, and will need to create another one.

You don't need to ask your brother to do this - he should sign out of your ID as soon as possible: if he starts purchasing anything it will be on your account and once he's signed out he won't be able to use it (but you will have paid for it).

To change the ID just go to http://appleid.apple.com and sign in with the ID he's changed it to and the password, and then you can change the ID.