You could consider speaking to a therapist/counsellor yourself as suggested by @ckwmum. This might help with strategies for what to do now.
If you or your husband work for an organisation of any size, you might have access to an Employee Assistance Provider (see
https://www.eapa.org.uk/find-an-eap-provider/). Using an employee focussed service might seem an easier, less threatening and cheaper way in to talking for your husband. They often offer individual and/or relationship counselling through these schemes and they're confidential, though usually time limited.
He also might not want to feel "sent" or pressured to go for therapy. Clearly saying you think there's a problem to solve and want to investigate solutions in a calm way, without trying to force him to do anything, might get through to him at some level, even if he doesn't currently share your view.