Knowledgeable answers please!!! Buying house & current owner breaking agreement!! Long due to details!?

I will try and sum this up as best as I can. I’ve rented the house I live in for 3 years now. No lease or contract of any kind was established (I moved in with the landlords’ daughter who is my friend and within a couple of months backed out and moved back home to her parents’ house).
One day an investor knocked on my door inquiring about buying the house. He informed me that he’d seen it for the 2nd time in a row on the foreclosure listing and wanted to know if it was up for sale prior to it foreclosing. What!?! That weekend (on Saturday) I look it up online and sure enough…2nd time in a row and it was scheduled to go to auction on that following TUESDAY! I call my dad and since it was pretty much going up for auction for 5-10K of what was owed on the note still (less than half of the worth of the house), he was interested in buying. I told him I’d speak to landlord and see what was going on. Well, sure enough landlord calls me to collect rent for that month and I tell her my findings. She made excuses, and I told her abuot my dad’s interest in purchasing and she agreed immediately. She didn’t want it to go bad on her credit and said we could just pay it off and that was fine with her. She was to LOSE the house in 2 DAYS! So, come Monday, chaos. We’re trying to get it out of foreclosure and they asked for a chunk of change to reinstate it. The landlord didn’t have the $ to pay so she calls me and then I talk to my dad and we agreed that if that was the only way to do it, then my dad would put up the amount they were asking with the agreement that she would turn around and sell the house to us once she was back in good standing and house was saved from being sold in auction. We succeeded at reinstatement and she signed a Promissory Note, which I notarized (I’m a notary). The promissory note states that they (her and hubby) were in agreement that the money we had just sent to her mortgage company was pretty much our “deposit” on the house. States that in the event that reinstatement did not occur or anything else prevented sale of the house to my dad, she’d be obligated to pay the entire amount back to my dad. The note talks about her agreement to sell the house for what was owed on the mortage w/out any further fees to be assessed or expected-besides closing costs, which my dad would be responsible for.
My dad hires a title company to do all the paperwork and they established the first set where the owners give consent to proceed with the paperwork and contacting their mortgage company in an effort to pay off their loan and transfer title, etc. So far so good…until it was time to sign away the house-they stalled. This is as of last week. Turns out her husbands didn’t know anything. By that I mean, he didn’t know the house was in danger to be lost much less knew about the sale of the house or anything until the very end. She didn’t tell him either! We found out after seeing the pay-off quote to her mortgage that she had failed to pay a single payment for 8 months. Then she lied saying her mortage was $ 300 more than what I was paying in rent so she couldn’t afford it….turns out her mortgage is like $ 8 less than what I was giving her..sure she wasn’t making any profit, but she had the mortgage payment every month.
Anyway, title company called them to tell them to come in and sign and then she turns around calls me and tells me that they were going to need $ 5k at signing or her husband wasn’t willing to sign. I asked her to tell HER HUSBAND to contact my dad so that THEY could discuss that. She said she would have him call…but she didn’t…she ended up calling my dad herself telling him the same thing she told me. Greed! How dare she!
Now, my question (yes, I’m getting to it)…isn’t she breaking the agreement to my dad by asking for more $ when the whole purpose of that contract was for her to not pull this kind of crap? If her husband is the one who refused to sign, why didn’t she who the day and time she told the title company she would? I mean, if he doesn’t sign and the deal doesn’t follow through, then she loses out on the $ she thinks she’s getting, will lose the house b/c apparently they can’t keep up with the payments and still owe my dad $ 7500! If my dad agrees to her demand just to get it over with (which is what he plans to do), when she accept that money, isn’t she breaking her initial agreement legally binding her to do as she said? Wouldn’t my dad then have the grounds to turn around and say, you owe ME back the money that I put up front since you didn’t keep your agreement to me??? FEEDBACK PLEASE! Sorry so long!
I knew I forgot something-I’m in Texas.

Yes, I know that it was a very risky thing to do this and that we are NOT realtory, investors, lawyers, a mortgage company or any other profession that would have allowed us the knowledge to know exactly what we needed to do and what steps to do it with, but keep in mind that I state we had 8 hours in which to work with or they would’ve lost the house if we’d taken any longer. Actually, we didn’t get the money wired until literally, the last minute (might’ve been a few minutes past the deadline the mortgage company gave us in which to wire the $ to them).

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