Can the sale of my house still go ahead?

My ex still lives in the house we shared and have a joint mortgage on. It is currently going through sale (offer has been accepted, initial solicitors paperwork has been completed and signed by us both and we are now awaiting the searches being completed & paperwork from the land registry) and we have been told that all being well, it should complete in around 4-5 weeks.
However, due to reasons I'm not completely sure of, he has been sectioned this weekend. Can the sale of the house still proceed because the process began in February (before all this happened) or will it have to wait until he has been released? I've no idea when this will be. Do I have to tell the solicitor/estate agent or can I leave it for a few days until I know more?

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