Search Results: let down by someone

OK, here it goes.

I matched with a girl on Tinder a while ago. She seemed like a normal, down to earth girl, we had a few things in common. I wouldn't say I was in love with her personality, or it was 100% match - not by a long shot. But I saw potential.

This was the picture she submitted to Tinder:

After talking a while, we decided to exchange facebook accounts.
When I looked at her profile, turned out she looks more like this:

Now, I am not exactly the most handsome guy around. But for one, I feel deceived. The picture she submitted to Tinder looks literally nothing like her. Which I guess I could have expected... But I did not.
And I really want to avoid sounding like an asshole, but let's just say I don't find her in the least bit attractive. I don't want to criticize her appearance, because I already feel horrible about the situation, but you get the drift.
And I will be honest, appearance and physical attraction IS relevant to me. If this was a one night stand, maybe. But she is looking for a long term relationship, and I don't want that with her. There's a zero percent chance of this working out.

The problem is that I foolishly agreed to a date at a non-specified time on the weekend. I could probably tell her some bullshit about not being able to make it, but that doesn't solve the issue, just postpones it.

Right now I see three options: Either I
-tell her as it is that this is not going to work out and that I am not attracted to her
-lie that I have something going on with someone else
-or ghost her.

I know probably the best course of action is to just tell her. But frankly, it sucks, and I am probably looking for some encouragement, or understanding. I am not experienced with these kinds of situations, this is pretty new to me.

So what would you guys do?

For the record, I am asking this anonymously because I don't like talking about my private life with people knowing who I am.