I'm not a lawyer, so this isn't legal advice. For that, you need a lawyer. However . . .
You acknowledge there was no signed purchase agreement. I understand you were willing to put money down to hold it. But--for whatever reason--that never occurred. There's no such thing in real estate as "implied purchase."
Reading between the lines, the seller probably was pretty stressed. The electricity may have been shut off. She's trying to coodinate contractors on a property you acknowledge was "pretty rough." Then--and not picking on you, but just explaining where she's coming from--you're making repeated requests--turn on the electricity, warrant the mechanicals, address a problem with the ceiling, etc. Now, all of these may be reasonable, but she was just eager to get rid of the place. And you weren't even buying outright--but just on contract. So somehow she got another offer--undoubtedly for the property in "as is" condition, possibly for less than you were offering. And she took it, with great relief.
Bottom line: Someone else offered her a deal that was more attractive to her. And you had nothing in writing, except your offer to put money down on the property.
One suggestion (and it's not necessarily to use a Realtor): What investors do in cases like that is tie the property up. They'll put a contract on a property with what are called "weasel clauses"--contingency clauses that allow them to get out of the deal after they've done their due dilligence. "Subject to approval of partners." "Subject to an inspection satisfactory to buyer." Things like that. So you tie it up with very little money at risk--maybe $100--and then you do all the necessary stuff. Either that, or you tie it up with an option. Pay an option of as little as you can--maybe $100, maybe more--giving you the right to purchase the property within the next 90-120 days at an agreed-upon price. Again, you're buying time and you have very little at risk if the deal doesn't suit you.
Hope that helps.