Hi Shiggs,
Sorry you are going through this and I completely understand the desire to protect your children.
My situation is slightly different, ex left 4 years ago when mine were 14 and 16 and has shown little desire to be a father since (though of course that is all my fault). He immediately moved 150 miles away to be with his girlfriend and thinks sending a text every few months absolves him of responsibility and makes him a good dad. He hasn't seen the youngest (now 18) since he left and she's really struggled with this and developed MH issues, and only seen the eldest 5 times in 4 years. I used to try so hard to facilitate things between them all, this is never what I would have expected or wanted to happen - but all you can do is be the constant in their lives.
However that doesn't stop him writing similar emails to what you describe, they'll see the 'truth' one day, how would they feel if he died, and right down to how good he is to pay
child maintenance still. It's pure emotional manipulation. I only ever said to the kids that he's entitled to his opinions and they should be able to make up their own minds but it causes upset every time another one arrives. And I want to shout from the rooftops what tosspot he is but I don't, I just hug them.
Obviously none of this is court ordered like yours. Hopefully someone here will be able to advise you on the legal aspect. But I just wanted to let you know you weren't alone in dealing with an ex like this.
Could your children decide themselves not to open the letters ? Maybe they could store them in a box until they are older and more able to deal with it ? That way you aren't obstructing the court order but limiting the damage and emotional distress caused at this time. It's hard for them to have to make this decision I know. But it does sound as though your ex is ramping it up now things are finalised.
As for the finances, yep we're the same, money is very tight here, whilst he seems to live the life of Riley. But never let that bother you if you can. I would prefer the love and respect of my two over any amount of 'luxury'. He'll never have that so that makes me the rich one in my book.
Take care.