Its difficult, because tbh if he was so violent with you I wouldnt like him near her at all.
But generally, I think in terms of boundaries if its OK for DC to cosleep with one parent, it should be OK for them to cosleep with the other
If shes bottomless in your bed, she will think its ok to be in his. And 5 is little, I assume he baths her so he will have seen her bits anyway. And if the issue is you feel he could be a danger to her you need to contact the police and/or SS.
Things id consider to help me reflect on if I had something to worry about:
why does she cosleep with him - does she have her own bed? or room there?
How do you know shes bottomless in his bed too - did she tell you? Did she say something concerning?
Has she said anything? Or started having accidents? Behaving in a concerning way?
And if i wanted to reinforce boundaries id treat her in my home the way I expected XP to I.e. if cosleeping is a concern at her age I would get her a bed at my home too.
If theres no real concern I dont think 5 is too old for sleeping with a parent of either sex