Domains - the name listed in whois is the owner of record.
Hosting - the name listed on the account. The other party should get their own hosting account (any pre-paid hosting should be pro-rated at 50% to the other party).
email -for each PAID email account, the name listed on the account is the owner. For freemail accounts, you don't "own" them anyway, so each of you just get a new account already - it's not like it costs anything - then set the auto-responder in the freemail account to give both your new email addresses, then give the account login info to someone in trust who will change the secondary contact info and login to something random. Or give it to the kids (if any).
data - you each own your own data, as per copyright. Whoever created the original data, they own the rights to the backups as well. Be nice - share anything that the other person is in, such as pictures, since they also have a right to those. Exceptions: "intimate" pictures - give them to the person who is in the picture and destroy any other copies - don't you even think of "sharing" those without permission, and you'll end up with a police record, same as Libby [last name redacted]'s ex boyfriend did when he "shared them" with her parents, grandparents, etc.
social media - why is this a problem? Social media accounts are not "property" and you do not "own" them, as per your contract with whatever provider you're using. If this is about a "family" account, each of you create an account under your own name, post a note on the family account pointing to the new accounts, then as part of the agreement the family account is either nuked, or given to a 3rd party in trust who changes the contact information and password, then deactivates it.
It's a divorce - the two biggest words are move on. None of the stuff listed above is worth fighting over 99.999% of the time.