Onit, delurking again to say in this day and age no-one is going to blink you having a gentleman friend over. You're in a new house - as far as the neighbours are concerned LCB is your ex, if they are aware of him at all. Who's going to think it's any of his business, let alone go to the bother of tracking him down and telling him?
And frankly if he has an issue with it and tried to raise it in court the judge is going to give him a long hard stare, raise and eyebrow and think "Aye, she's well shot of that numpty."
Life goes on. You can't live it in fear of how he's going to react -because he's never going to react to anything you do well. Because he's an arse. You will always be in the wrong as far as he's concerned, because he's an arse. Why on earth would you want to give his opinion any weight? He's an arse. Any fuss he kicks up can only serve to further reveal him as the arse he undoubtedly is.
You're single, horny and the kids aren't in, you have a nice chap who makes you feel fab. You're allowed to have this. What's he going to do in reality? Be an arse? Been there, done that, you've survived and you're making a new happy life with him as an irritation on the periphery, and he hates that. LCB can huff and puff all he likes, but guess what? He can only stop you if you let him.
And the new Onit - or rather the Onit that was always there but cowed into submission but who is now free and brave and magnificent - isn't going to let him stop her doing anything.