My DDs teacher did her dissertation on how divorce doesn't necessarily mean unhappy kids, so there is research out there
It’s the living with conflict that makes kids miserable, rather than their parents not being together. Both conflict within the family before it breaks up and then the myriad possibilities to continue that conflict after separation.
There’s absolutely no reason why divorce has to be damaging to children if the adults can be decent humans about it all. Kids can grow up happy and healthy in all kinds of different family set ups. Sadly, many people are just too caught up in fighting their ex and the kids become collateral damage.
I have every reason to hate my ex. That’s why we split up. But I have to continue to deal with him to support DS as he grows up. So I set my feelings aside (as does my ex) and we put DS’s needs first. DS is happy and is not harbouring hopes we’ll get back together or anything. He gets plenty of time with both parents, and we consult him about things where decisions need to be made. It’s extremely low conflict all round.
I’m always positive about his time with his dad too - I don’t try to make him feel guilty for loving him or enjoying spending time with him. Nor do I go on about how I miss him or how it’s awful that I didn’t get to do X with him or whatever. If DS is with his dad on his birthday, for example, I focus on the fun things they’re going to do and don’t even hint that I’d rather spend his birthday with him. It’s not about me.
My DH’s post divorce situation is different. His ex is a high conflict person generally. And DH is both irritatingly argumentative, a bit goady and often focused on what he wants (rather than the kids). It was a high conflict situation pre-separation, including violence from their mother even post-separation (she started kicking and punching him at the school gate on DSD’s first day at school because he’d annoyed her - almost certainly on purpose).
Arrangements for the DSC are pretty much always determined by their parents’ wants and they often argue about it. His ex has withdrawn contact just to force him to do what she wants more than once. The kids are increasingly manipulative because they know they can tell their mum things (often lies or exaggerations) and she’ll go mental and start shouting at DH down the phone. DH would be just as bad (except that I keep telling him how fundamentally awful this crap is for the kids, and to be the grown up and bite his tongue).
All of this definitely does affect the DSC. Their behaviour is pretty terrible and they’re both really quite weird in various ways. It’s not because their parents divorced. It’s the way they divorced and the way they continue to see the kids as a ground to be won. The DSC would be the same (possibly worse) if they’d stayed together because they’d be living with constant conflict. The entire relationship was like that (apparently) and the DC’s affections were a prize to be fought over long before they decided to call time on it.
That’s what screws kids up.
The really hard thing about separated families is that you just can’t force your ex to behave well. All you can do @Lovelymonkeyninetynine is to behave well yourself and hope he does the same. Hopefully he will.
It’s a good idea to make a parenting agreement that covers the key points, and then to just trust each other to parent in their own way beyond that. Children can adapt to different rules and situations in different houses, and trying to control your ex’s parenting just leads to misery all round. It’s important to recognise that your ex will do things you would never do, and just let it go (obviously there will be red lines - but that’s what a parenting agreement can cover).