She talks to me and is sure to put extra emphasis on the fact that she recently broke up with her ex.
Sounds like she wants a rebound perhaps.
Is it worth starting a relationship with someone who has only shown interest because she's recently ended another relationship.
Also, you don't find her attractive. So why have a relationship with them? It's kind of the point that you should be attracted to them, and yes, both their character and their looks.
As for the other girl, you could tell her that you like her too, but she'd have to leave her current boyfriend.
You don't want to be an affair.
And you also have to consider if she's likely to dump you for another, if she'll do it for you.