Horns, it's honestly pretty selfish to deny the truth because you're worried they will forgive you. It's up to them to decide if you 'deserve' forgiveness for what you did to them, and not you
Amd there really is no better time than in the party, while you're still Asriel and not Flowey. You don't have to right now, but keep it in mind, alright?
Horns: Selfish? You don't even know what I did!
Horns: Plus, it's a lot harder than you think. I'll have to tell them everything before I can apologize.
Horns: And they shouldn't be able to decide! They're a bit of a pushover. Frisk actually-... Ballin, I guess, they reminded me of Chara a lot before they grew a spine.