First of all, if its really your good friend, you owe her the respect as a human being not to fuck her. Just be honest but gentle and make it a point to explain that in no way do you find her unattractive objectively, you just have other preferences and your friendship is too important to disrespect or risk.
If you want a selfish approach, treating her with respect will have her talking when she's not so upset about rhe recent loss and get you 5 times the amount of pussy later for being a good guy.
And just an FYI for some of the posts I see in this thread. I can grab 10 average to chubby guys out of my office that can pull pussy better than 90% of the people on this board. Pussy way out of their league in terms of looks.
They don't have muscles or 6 packs but they are the best salesmen I've had the pleasure of working with.
And these women absolutely adore them. Not one talks about or shows off how much money they make and the women they pull are all high value professionals.
Want to find a really good woman, learn to sell.