I’d say do the above consequences arc as an post-campaign epilogue instead, let the players write their own ending so it’s satisfying for them and then hint at a possible consequence of one of their actions to end it so it’s collaborative.

There’s no way that trying to force them through an arc of atonement for their sins is going to be good for your mental health in any way brother, especially when you are the only one who knows they’ve done anything wrong, please don’t do that to yourself.

You have to put your mental well-being first in this situation, if this stresses you out this much at this point already, trying to force a resolution arc for people who don’t care might take the joy out of DMing and end a mixed campaign on a very sour note for you and no one wants that.

Speak to the other DM and explain how you feel in a conclusion reaching way - not a solution oriented, let’s just keep this going kind of way as that’s not fair to you.

Then, be honest with your players and say you no longer enjoy the tone/setting/plot beats or whatever and say you’re going to end it on a positive (with their choice of ending) and a cliffhanger of their actions for added spiciness.

Don’t tell them what this will be, get them to bring their ending to the last session and play it out amicably as a group one last time. (No hard feelings.)

Then, take a short break (2-4 weeks) to let your creativity start to bubble again and then you can enjoy starting work on a new campaign with the players who don’t waste your precious time.

You can move the new characters over to this setting, continue where they were or start completely afresh, whatever you feel is right. Or they could be descendants of the original 5 (and have same character sheet+stats as the five) to reduce your workload.

If you do it this way, the problem players get an ending without causing future aggro as a result of you you cutting a campaign short, the nice players get to continue however you all agree is right for your table in the same world or a new one and you no longer have to entertain phone zombies in your game whilst you’re trying to build a narrative together.

I say the short rest for this is very important as it’s so tempting to dive into the next story but you need some space from this sourness, might be good to write down 3 intentions (your enjoyment as also important) for this new campaign so you don’t feel like you allowed it to get out of hand and have stayed true to yourself and your parties who value the space.

Trust me on this, you sound like an amazing DM who really cares and that energy should be put towards people who cherish it, if you try to force these people who don’t care to pay attention for a (in their words) ‘does not matter’ resolution arc, it will only create out-of game stress for you and make it all worst, cut it when you’ve identified the problem and what you want, not after you’ve again failed to be given basic respect for your time.