I'd assume if you fall at lvl 11, having founded quite a majority of your career, it may be easier to apply for a delevel to 10 and continue from there as a new class, or remain at 11 and be comfortable that's your limit until you've atoned.
You'd be 'losing paladin powers' still, effectively, with the delevel. It'd be reason enough to consider it, but once you multiclass then you no longer can progress as a paladin, losing the ability to atone.