That being said, I would highly suggest you talk to a CPA/Real Estate Attorney to find out all the implications of such a decision.  

Keep us posted with your ultimate decision and how it works out for you.I wish you the best!

the 40,000 is her decision.

All in all, his poor business decisions will bite him hard someday.  

I need to make this decision soon, it's only my second flip deal so of course I get that questionable feeling especially with so much money but the potential to double it makes me want to go for it.

If it's not, then don't.I can understand it upsetting you, but keep a level head and treat the deal like a business decision.

However, I'm not sure if that's a wise decision considering that I'm paying the taxes and on top of that if I start working on it and I invest all this money I could end up not getting the deed.

As you do, take notes, and I suggest that before you do another investment, have a plan for dealing with the taxation.In every deal I have ever done, taxation was one of the three or four decision factors for buying, selling, holding, etc.  

Assuming that you made wise decisions with the cash...   

If they comeback with a counter then it's YOUR decision at that point to compete with others.