Escaping Double Backslash in Rex/Regex Command

I'm having some serious difficulty in figuring out how to escape a double backslash within the REX/regex spl command.. The following regex works on regex101 `"title\\\\\"\:\\\\\"(?[^\)].*)\\\\\"\,\\\\\"selection"` when extracting the log snippet below to get the "Button Title" text: > "partyId\\":\\"lahflkhasdljkflkf\\",\\"title\\”:\\”Button Title\\”,\\”selectionType\\":\\"button\ I found a suggestion on "Tricky behavior of escaping backslash in regex" to \\\\ to match a single \ but that didn't do the trick. Anyone have advice on how to escape a double backslash in the rex command, and if so please post the regex below! Thanks!