[] Refuse, they don't need to know.
[] Delay, you'll be able to tell them after Walpurgisnacht.
[] Madoka, she deserves to know your past.
[] A partial truth, tell all of them about your time travel.
[] As much as you can bear, tell Mabayu and Sayaka of the time travel, tell Madoka all you can.
1 is falling into the worst of old habits, which is arguably the biggest reason Homura had such a bad time of it in past loops in the first place. Though, one could argue that by already kinda breaking said habit, we could afford to fall back into our comfort zone. I disagree.
2 is just stupid. In the first place, it assumes an "after" even exists, which frankly I'm not convinced will be the case for all of us. Wally is basically an Endbringer in all but name here, after all, and that means character death on a good day.
3 or 4 is probably equally fine, except we may need to pass a similar check to before. My only concern with 4 is that we may be stretching our trust too thin.
5 is... This could potentially make Madoka go kinda Yandere for Homura. Because if she believes it, she'll know the true depth of our love/obsession/commitment. All the suffering we've been through, for her sake more than anything else? We'll be lucky if she doesn't hit a Second Trigger from the shock. Potentially, it may also Second Trigger Homura because she'll be battling every step of the way to get all her trauma out. Personally, I don't want to Second Trigger Homura because I kinda doubt I'd like what that looks like. Plus, there's always the potential we ST against Wally cuz we failed again, and boom our loop power is back. Doubt it, but it's possible, so from a meta perspective we should try to save our ST potential until then.
Of course, that's assuming we even Triggered in the first place instead of something imitating the Trigger Phenomena to make us seem more "natural" to the Shards, and there isn't just some arbitrary magic bullshit threshold we gotta pass character developmemt wise to regain the remains of our tool kit.