Hmm... so you're looking for a walkthrough of how to get to the Sans FIGHT.

You really wanna FIGHT him that bad?

Well, okay. If that's what you want...

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To complete a True LOVE (No Love) route, you must have already played through Act One. Note: Act One is the first playthrough in which you start with the stick.

Once this is complete, Flowey will give you a knife after you RESET.

You will have to play through at least seven (7) times, killing a different combination of monsters each time.

You MUST encounter this screen counting down how many combinations you have left. If you do not see this screen, your run did not count.

Here are the combinations in a suggested order.  Please note, you don't have to complete it in this order.  However, ending by killing everyone allows you to go into the Sans fight with the most HP. 

** There are seven (7) total death combinations you must play through. Note: "Alphys + Undyne" together counts as one (1).

1. Toriel
2. Papyrus
3. Alphys + Undyne
4. Toriel and Papyrus
5. Toriel and Alphys + Undyne
6. Papyrus and Alphys + Undyne
7. Toriel, Papyrus, Alphys + Undyne

Once you play through each combination all the way through, Sans will finally acknowledge what you're doing and engage you in a FIGHT. Also, make sure to save the butterscotch cinnamon pie for later. That will allow you to heal during the FIGHT.

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Hopefully, it's what you were looking for.
Hopefully, it's all worth it to you.