Facebook: Don't Do This
There seems to be a pattern during breakups of changing passwords to the other person's Facebook account.

In Texas, this often constitutes a crime sometimes a felony. If a message is posted under a false identity or a private message intercepted, this often is an additional crime.

It may not even be necessary to change the password or make a message under a false identity or review a private message to commit a crime. Simply signing on to someone else's Facebook account without permission all by itself may be a crime.

These things are probably true in most if not all states (and these things may also be Federal Crimes).

You should assume that doing anything at all with another person's account that a member of the public generally cannot do may be a crime, and it may be a serious crime.

I think many people don't realize this. For older people, doing this can be roughly compared to wire tapping.
Just don't do it.

Don't sign on to or change another person's Email Account, their Bank Account, or really any account belong to them. If the account is under their name, if they set the password, or they primarily use the account, it probably is their account.

Don't assume you have permission to use the account simply because they once gave you the password. If you are breaking up, you should assume you no longer have permission to use the password. An account may be "joint" but be careful.

If you need to access an account and your right to access the account is debatable, ask permission. It just isn't worth being caught up in an unintended crime. If you need something on the account and permission is denied, it is time to hire a lawyer, if you haven't already. Do what you need to do openly and if you cannot get consent, then ask a Court to help you.

If you are going to access a debatable account without permission and without court help, do it very openly. Don't hide what you are doing. Openly claim you have the right to do it. Yes, the other person might change the password, but it is always better to do debatable things in the light of day not at night.