I think you are too nice and easygoing, OP! I think it's time to get tougher.
Background... ex and I broke up. Very amicable. No maintenance paid. Still sleeping together family days out etc. He was a bit of shit about money. Conned me into taking nothing
No wonder it was an amicable break-up - what's he lost exactly?
Spent a whole day in bed together on Monday. He love nobody like he loves me and all the rest
Love talk to keep the sex coming.
Told me today as I’m taking dinner out of the oven, he’s seeing someone
What a callous way/time to drop that into the conversation. At least he made sure he got his dinner first!
He sounds completely selfish and mean. Time to get the money you are owed. Of course, he will spin this to the OW that you are out for revenge, but bugger that. This is something that should have happened before. Toughen up OP and fight for your kids' welfare.
Stop sleeping with him - you don't know he practises safe sex. He won't care about your health. He already doesn't care about money for his kids or your feelings.
Now that his little romance is out in the open, you may even find he spends less time with you and the kids anyway. I hope I am wrong, but he sounds like the type who would put his love-life before them.
By the way, what did you two break-up about anyway?
I am sorry you have all this to deal with OP, but you are too good for him - that's the bottom line 