Nobody will be laughing at you. I've never read an affair thread that has left me so incensed on your behalf.
Whether you like this or not this is being played out in public, your friends and family will know and I'm a firm believer that it's best to get the truth out in the open before he rewrites history so that you were the bitch from hell, your marriage was dead, they tried to fight it etc etc.
I'd post something on FB like "some of you will now know that fuckwit and I have separated. If you see him with his new gf, that is why. Sorry for doing this on FB but I've been completely blindsided by his affair at work (actually in the office - nice), so I can't face telling everyone individually at the moment."
Don't let him hide behind faux concern for you, neither of them has an ounce of respect for you, they just want to hide their own despicable behaviour.
Who gives blowjobs at work to men who are shagging their wives? If I worked with DH I wouldn't even give him a blowjob at work. She sounds rank, but your DH is the real cunt here, he really is. Do not lose sight of that.
You're doing amazingly well btw, you're strong and wonderful and you don't deserve any of this 