Go back in time in time with your research; all the way back until you can't go back any further. When you think about your oldest relative on your family tree, how much do you know about them? How accurate has your sourcing been that they might actually be the wrong person on your tree? Can you handle the possibility that your research was incorrect? You must accept the unknowable.
Accepting The Unknowable
For example, the earliest member on my own family tree is a mysterious fellow named Gode Korling, some guy from somewhere in Germanic Europe born around 1210 AD. I found him very early on in my research when I decided to see how deep I could go on my tree. Whenever I found a name, I added it, regardless of if it was an accurate addition or not. I added it regardless of the strength of the sourcing. If there was a possibility they belonged on the tree, I added them. That went on until I finally hit a brick wall with Gode Korling.
I've prepared myself for the fact that Korling is likely a mistake. It is pretty damn hard to go back 8 or more centuries with any certainty unless your family was especially astute when came to all things genealogy. When I eventually find a flaw in my lineage that forces my research away from Gode, I will be disappointed but it will not be surprising. When that day comes, I will gracefully remove what remains of that line, break off that branch from the tree.
There is something that feels philosophical about this point. There is an eventual end to a family tree. We are all connected somehow to everyone else on this planet. Someone always begat someone else going all the way back; until a time when they didn't. Even if my research is impossible to continue back any further with Korling, it always would have stopped at someone. It is impossible to know everything. We must accept that life begins at a point where we have very little documentation and even less of an ability to prove where our lineage comes from. Take a breath and find peace in the process, not the end result.
Now, until I prove otherwise, I have a link to the past that reaches back to the 1200s. I am backfilling my tree, and may eventually prove that Korling does not belong. However, until that happens, I have a thread that I can follow to help point me in the right direction. I am comfortable with the journey; where my research has taken me thus far. I can be proud to call myself a member of the house of Korling.