Failed to parse XML due to: in epilog non whitespace content is not allowed but got t (position: END_TAG seen …t… @360:33182)

It’s my own fault I believe - I had one page open on two tabs and made a bunch of edits in one, then a couple edits in the other. Then some more edits in the first. 

Help! Is there some way to access the XML? I can’t even open the page for editing.