She's been a complete bitch, cheeky beyond belief, and said some truly awful, unforgivable things.
BUT
In a way, i do feel a little bit of sympathy for her. Cosmetic surgery is extreme, it's literally having your body cut open. The anesthetic to put you to sleep is a risk in itself, you risk all sorts of complications including infection, disfigurement, in very rare cases even things like paralysis, limb loss and death.
It takes a very unhappy person to weigh all that up and decide it is still worth it to go ahead and do it. Even if she doesn't have body dysmorphia, you can still be genuinely depressed and emotionally distressed by your physical appearance. (I speak from experience, i have congenital symmastia, and if i could afford the OP i'd seriously consider it)
She has effectively lost £13,000 of money that does not belong to her, and has nothing to show for it. Whether she tried to save up first or not i dont know, but she sounds pretty desperate to have saddled herself with that much debt all in one go. She is now going to spend however many years it takes her to pay it off, scrimping, saving, cutting back on luxuries, month in, month out to clear the debt, including however much ends up getting added on in interest.
She is no doubt heartbroken, not just about the money but that she went through all of this for nothing. Working herself up to deciding to go for it, applying for a loan and the mini elation she would have felt when she got approved. Booking it all in, being all set to go, then a week or so prior it all comes tumbling down over a misunderstanding/oversight. Cheeky to want the OP to pay half of the travel and hotel, but in her mind OP was going too so it seemed fair to split. She pushed when she should have folded, and it left her up shit creek without a paddle as she had no other option, and possibly/probably couldn't afford any other loan to hire someone, and as OP stated had no friends or family who could go in her place.
She said some of the most awful things a person can say in her panic/desperation to persuade/manipulate/scare OP to still agree to go, i do NOT defend those things what so ever and i understand OP's decision completely to no longer go along, i wouldn't have either.
But i just can't bring myself to be gleeful that she didn't find a solution and is now 13 grand plus several more on top in interest in the hole with no "fix" for her body insecurities, plus all the extra damage this has likely done to her mental health.
Best wishes to you Welsh with your journey of TTC, i really hope it works out for you.