The short answer to this question is yes.
Engaging in covert efforts to spy on your spouse is, in simple laymen’s terms, a no-no. Indeed, with the recent changes to Florida law to include and incorporate cyber stalking, it is potentially dangerous on a criminal level, as well. See Florida Statutes 784.048 (http://www.leg.state.fl.us/statutes/index.cfm?mode=View%20Statutes&SubMenu=1&App_mode=Display_Statute&Search_String=stalking&URL=0700-0799/0784/Sections/0784.048.html).
It is one thing if your spouse is careless enough to post information on his or her Facebook page, Twitter account, or other social media. The idea there is they effectively gave up any claim of privacy to the position and/or views expressed by putting them out in the world for public consumption.
It should be noted, however, that in today’s world of auto-password there is a viable argument to disavow such posts, since the evidence rules require that posts be authenticated before they would be admitted into evidence. In theory, an account owner can simply claim they did not personally author the post because they did not have control of their account 100% of the time (for example, they set their phone down or someone had access to their computer, etc.).
In short, the argument against the information you could gain by hacking is hacking.
The better course of action is simply NOT to be tempted with any involvement with online anything while the divorce is going on.
Moreover, if you each have access to each other’s passwords and account information, then with the exception of joint accounts you should each change your own personal information as soon as the divorce is filed (if you cannot come up with a solution to the joint account, then split the money in it and close the account).
If you improperly take advantage of a careless spouse who inadvertently allows you continued access and/or is careless with his or her security, and it comes about that you did so in order to take advantage of them in the case, then that behavior will simply serve to undermine your credibility when it comes time for the court to determine the difference between “he said” and “she said.”
Remember – judges are just people. They will relate to the sense of violation to the wronged/hacked spouse, who did nothing more but have the misfortune of being involved in a court proceeding with someone who took advantage of them. You do NOT want to find yourself at the tail end of that.
So the moral of the story is DON’T HACK YOUR EX. Aside from being distasteful and possibly illegal, if discovered it will also make you look bad. And in the arena of family law when your word and credibility is your best defense, it is simply not worth leveraging away your dignity and good name in search of data.
That is what lawyers and subpoenas are for.