Not too young to tidy his room. Very much too young to pack up his room to move house.
The emotions around moving, the feeling of uprooting, of uncertainty and of powerlessness in a huge life event will make packing a massive deal, for you, for him, for all your family.
He needs support. He needs reassurance. Doing it alone in his room would be miserable for him. Doing it together, him and his mum, chatting as you pack, reminiscing over the little stories and memories of playing / laughing/ being silly with his games/ tech / posters/ even his clothes turn it from a symbol of risk and anxiety, to a moment of togetherness and a reminder of old bonds.
Just a word on how you phrased something in your OP:
"But my 12 year old son thinks it's ok to still let me do it all an he does nothing"
That doesn't sound quite right somehow. It feels wrong because it's a slightly wrong power dynamic going on.
He's a child still, yes a bigger kid, almost a teen, but still a child nonetheless. He doesn't 'let' you do anything. It's the other way round. You let him.
The way you're writing is the way you'd wrote about a partner. Projection perhaps? It must be very hard to avoid seeing echoes of the abusive man in your son. But I think it's important that you look for the differences, not similarities. Your DS is 12, and therefore can be 'acting out' for so many many reasons, all perfectly normal (though annoying!) childhood dynamics and developmental stages. It will be far healthier for you and your son, to focus on the normal reasons first, even if you have that fear inside you that it's 'like father like son'.
I find putting the best possible (realistic!) interpretation of a child's behaviour tends to mean they live upwards to that. And vice versa. If he thinks you think he's like his abusive father, that's a massive weight to carry around. If you do really see signs that he can't deal with his anger / violent behaviour / hatred to women / girls/ you etc, then it would be time to get him some help. He would have suffered harm from seeing his fathers behaviour, and might need a helping hand through it all.
But that's very different from a young boy feeling angry and sad and scared that he has to move again.
It could be you're just venting and I've got the wrong impression. But I do think it's hard to separate out all this stuff in your position... proto- teen / normal 'acting out' / reactions to big life events / from the hallmarks of abuse. It's tricky. Especially when you're still under attack from this awful man, and there's so much healing to do yourself, your children and your family as a whole.
(I know this sounds bad but it has crossed my mind to be very glad my DS doesn't look like his abusive father. I don't 'see' his father in him so am not reminded of stbxh's abuse in any way. That's not a great thing to admit I know, but thought it might be useful in some way to you... ).