Dirty trick?

Why wait until tomorrow?

I would contact her today, as her whether she is going to chose your house or your friendship so you know where you stand.

Some people are just not very bright rather than overtly nasty. Social norms dont come naturally to everyone. Spell it out to her now before it is too late. If she then choses the house anyway there will be no doubting her motives later, she wont be able to crawl back claiming missunderstandings.

Or she might just not get it. And chose you.
.SPEAK to her. Today.

Thanks everyone for the replies so far and I'm glad to know you don't think I am being unreasonable to be upset by this. I should know tomorrow what is going to happen and will keep you up to date.

The thought of going to stay with her in May at what should have been our house is unbearable.

Yes, it's a very dirty trick and would you want a place on the same small complex as someone who would do that anyway? She might be thinking you'll buy another one there. I'd say the friendship is doomed.

Before the matter goes any further just lay your cards on the table and tell her that if she pursues then any friendship between you is well and truly over. A good friend wouldn't ever let this situation arise, so you're well within your rights to tell her (very nicely) to back off !

I'd cancel the deal and the friendship - when someone goes behind your back to take away your dream, how can you ever trust them again.

That is not my definition of friendship. Find another place to buy a holiday home and Do not tell her until she has completed her purchase, even if she is back to buying the house she originally wanted.

How spiteful and selfish.

You need to spell it out to her that if she does that, the friendship is over...I would be tempted to say that she has already seriously upset you.

A good friend?? I think not !?

Ask her why

That stinks.

That's not nice ?....dump her