The trouble with this forum is that each section is specific to a particular make and type of lenses. So you ask a question about one type of lens that applies to lots of other types, but only those interested in precisely the same type of lens as you are will see the question, and this reduces the chances of getting an answer.
Anyway, rant over...
I don't wear Focus Monthlies; I wear Focus Dailies, and I honestly can't say how similar they might be, but...
I've had
Focus Dailies break up in my eye on a few occasions, when I've been a bit rough rubbing my eyes. It also seems more likely to happen when I've been wearing the lenses for a long time (but never more than a day, obviously).
It's not that bad; in fact, I've had a fragment floating around in my eye for at least a day on one occasion; it didn't bother me much and I was wearing an intact lens as well.
Getting the bits out is a pain, because they don't float onto the centre of your eye like the whole lens does. They hide in the corners, and they're really hard to see. Once you've found one, with a good light and a magnifying mirror, moving it to a part of your eye where you can lift it off isn't too hard.
A good flush with some eyewash or wetting solution helps too.