I’m so sorry this has happened to you OP, I too discovered my then partner was living a double life - after a year. It’s the most horrific gut wrenching pain to realise all of it had been a lie.
He said he could ‘compartmentalise’ and therefore didn’t feel guilt as he was living two separate lives. It felt so real to me and I’ve never felt so loved, but I couldn’t have been as he couldn’t have done this if I was.
I spent 18 months crying myself to sleep, constantly asking myself how could he do that. Asking myself did he feel guilty, wanting him to be sorry and apologise. I would have done anything for him to come back because I was hooked.
Then, I realised all the reasons and apologies wouldn’t mean anything, he’s a dishonest liar and any apology or sorrow would also likely be a lie.
I stopped constantly questioning myself and wondering why me, and realised he’s a sad nasty little man who has not one iota of care about anyone but himself.
I know how hard it is, and I’m sorry to say this will take many many months to move on from. But please be kind to yourself and realise it isn’t your fault, you trusted and were proved wrong, but you aren’t the bad person
Make you and your daughters Xmas a lovely family time and tell yourself you’ll deal with this in the new year xx