A child can choke in seconds,
they can fall over and bang their head against something hard,
a fire can take over a house in minutes,
a curious child can find something sharp and shiny to play with or matches,
a child can get scared being left alone and scream blue murder which could bring on fever or fit!
Someone could break into the house, that only takes a few seconds!
Abduction! (ok very small risk but it does and can happen)
Need I go on?
I know you probably are aware of all this but please don't leave your son in his father's 'capable' hands again and put him at risk!
I don't know what to suggest but please try and talk it through, it's ok if he says it won't happen but believe me I and I know others have been in situations where 'it wouldn't happen to me'
Hope you get it sorted, good luck with it and with the new baba!
xxx