As far as actual computer security, there are many small programs or apps that clean your web history. The smallest, safest, and most comprehensive is "ccleaner" Google it. There's no sypware, and it's fast and VERY effective. It works up to windows 7.
You have to use this after every browsing session to keep the history clean. NOTICE, THANK GOD, this won't keep cops from finding illegal stuff, (they can call up stuff from YEARS back, ) but it will keep out kooky spouses.
AFA your STBX, or whatever, snooping on this site looking for you, my next suggestions would be change the sex and ages of your kids in your NEW signature AND posts. Minimize or eliminate any mention of his fambly, and your fambly. Don't mention financial details like houses, apatments, day care, jobs, cars, etc.
Let's face it, he's found the site. At this point, your options are to abandon it, which you obviously haven't, or to keep on with your active advice-giving role while starting a new persona (new log-in!!!!) seeking support which is covert, and does not give him identifiers which he can use to follow you in your quest here.
Start a new logon, leave out the hard details like kids, in laws, school dates, etc. you can still post and get support here regarding your situation.
Don't post with your new personna tommorrow. That would be too obvious and easy for him to find.
Wait some time and THEN post, have your alternate data set in your head, and make posts that aren't obvious to him in the details.
I know it's be tough to be that vague and still describe your sitch effectively, but you can do it if you really want to.
Best, Punkt.
These are my friends now!
But someday baby... You ain't worry my life anymore
Take away, take away what I don't need, save the good part please. Fade away, fade away.