you have been very generous

and they are repaying you with the reverse

You do not need the stress.

You do not need your very young baby looked after by irresponsible people. The care of a young child, the care takes precedence, not points scoring. You don't need Jim to get bad nappy rash before they listen. The father should listen purely because it's in Jim's best interests, to be changed correctly, for his health. And because you have primary care, it is natural you have more experience of what Jim needs, and have more practice in doing it.

i hope due to Jim's age, and feeds, that he is not out of your sight for very long (for your and Jim's sakes).

You do not need your parenting to be mocked/undermined, you're a new mum, dealing with so much, and doing so well, you need to be supported, not torn down.

You are the mother lion for your darling boy. I hope the counsellors give you suggestions on what to do. Can you see a one to one counsellor, as well as mediation counsellors?

There are issues it would be good to get advice on, by yourself, without your Ex present.
And with mediation, the counsellors have to be neutral.

I think you are a great mum, is there any reason you feel compelled to put up with twice weekly visits (in YOUR home). It would be very different if those two people were respectful, but they're not.

I'm sorry this saga is continuing, you and your son deserve better.