Since I am about to graduate with a degree in psychology and I have a mother with Borderline Personality Disorder, I just want to add that this is very consistent behavior with Borderline and Bipolar.
In a good phase, you are loving and generous. You are charming. You spend money you don't have and you pick up hobbies etc. that you don't have time for.
Then things start going bad. You suddenly are paranoid that those who you liked and trusted hate you. You feel that you are scum of the earth. You owe money you can't pay. You don't have time to keep up with the commitments you agreed to. You withdraw suddenly.
If Betsy is suffering from a Borderline/Bipolar downturn, it really doesn't matter WHAT you say or do, or how nicely you say it. She will perceive you to hate her and are set against her. She will black list you and react with defensiveness and anger.
My advice: pool money together and one of you go to her place and get all the loaned snakes back. If you show up and ask, she will hand them over, I'm betting. If she made a down payment to you, pay it back to her so that she doesn't have any way to take legal action against you.
I have friends and acquaintances who think my mom is the best ever. Generous, fun, kind, full of life. They don't get to see her dark side- too bad for me, I got to live with the terror of it all.
If she has BPD or is Bipolar, she can get pretty downright vicious, believe me. And neglectful of her responsibilities including the snakes.
I've had my mom, who rescues homeless pets and does catch-and-release spay and neutering, neglect animals to the point of extreme suffering and death when in a bad turn. Dogs thirsting to death, cats living for months in cramped travel carriers with ears full of ear mites, etc. When she is well, she is the BEST animal person ever. I've had her babysit my animals for me- and she checked on them multiple times a day- Played with them constantly- perfect, loving care.
Don't be fooled, just because Betsy WAS nice and WAS competent doesn't mean that she ALWAYS is.
A big clue of Borderline: inconsistent black listing of people/entities. The Borderline will tell you that so-and-so is making their life hell-on-a-stick. The story will change. Next month they won't remember what they said or who they told what. Sometimes YOU are the hated one. They are always being persecuted by someone. They pick up new hobbies/careers/education paths all the time, then drop them suddenly. Sometimes after putting a monumental amount of time, effort, and money into them.
(For example, my mom got into photography. She got THE BEST equipment, despite being out of work. She started a degree in photography. She won awards. Then one day, she dropped out of school, sold her camera, and took her ribbons down and put them away. Then she was crazy about graphic design. She started a degree. She bought the best computer and software.... then it was farming. Bought a house, land, goats, pigs, alpacas, a llama... then it was moving back to the city and do computer programming. ?!?!?!?!)