Hi Lou, hope you are keeping as well as can be hoped in the circumstances.
Your STBXH's behavior is shocking, awful and sick, but I think I can see from some of the patterns what type of person he is and how he deals with things.
It seems like from start to finish he has dealt with his lying, deception and bad faith by inventing some version of events in which he is blameless, and then acting it out. When this goes wrong he blames other people. mainly you for the fallout. I would say this is classic narcissism - it is like a reality filter that doesn't allow anything through that reflects badly on him.
First was the situation when he was cheating on you. The utter effrontery of what he did is almost unbelievable - attacking you for being paranoid about his work meetings. In this little world in his head, he actually was at work all those times and you were the jealous, suspicious little woman at home, who didn't understand how much important work he had to do.
I am pretty sure that he also reinvented the situation for the OW too. No doubt he was either 'separated', or 'about to be separated', and you were painted as the one who was pushing him out into her arms.
I think the chutney situation might have been for the benefit of his parents. He knew what he was doing was unforgivable, not just by you, but by anyone reasonable who knew you both.
What he was trying to set up was 'I made mistakes - but Lou threw me out without any hope of coming back'. It simply makes no sense for someone to leave taking everything they own including kitchen utensils and food, but then be setting up counseling appointments a few days later. But what if you had put his possessions on the doorstep and told him never to come back? Full of remorse, and wishing for nothing more than reconciliation, he books the appointment. But you were so hard-hearted that you wouldn't even let him collect the letter, let alone go to the counseling, closing off all possibility of saving the marriage. No doubt his parents heard something like this. In a little while your 'side of the story' will be erased from history, leaving his new child and partner as the natural progression after you destroyed the marriage.
Undoubtedly the OW got some BS story like this too. After him trying to be honest with you about his mistakes, you were so vindictive as to not let him see his baby at the scan, concerned father that he was. The catfood is another little setup - he is filled with concern for the poor cats, you won't allow him to see them. He was probably hoping that you refuse the food angrily - so that he can play the victim some more - desperately worried in case you are starving the cats to punish him.
It sounds like his parents will eventually be happy for him to pull the wool over their eyes. The question is whether the OW will too - or whether she will soon be catching you up in realizing what a dangerous, manipulative little psycho this man is.