Hello OP, I'm so sorry to hear this.
As a PP mentioned, your children reaching the age at which he was first abused can be a common trigger for long-suppressed trauma to resurface.
It's really encouraging that he felt able to tell you - male survivors often feel they are under a heavier burden of shame and silence than women so it's testament to the strength of your marriage that he trusts you enough to share this with you. He may feel very fearful as a result of disclosing this long held secret.
I would not suggest taking him to A&E unless he feels in danger of harming himself - there will be a very long wait and very little treatment beyond a referral, which should more properly come from his GP.
For now, your best course of action is to reassure him that you will support him in whatever he needs, be that therapy, time off work, etc. The way he is feeling now might feel completely overwhelming to him but it is absolutely normal for abuse survivors and he is not "going mad" - he is having a trauma response, and he can and will recover from this.
The following organisations may be helpful
https://napac.org.uk/ (closed weekends)
https://www.survivorsuk.org/ - for male survivors. My late husband was involved in this organisation. Their chatline is open tomorrow from 12-8pm. They also have a section on their website about how to help a loved one:
https://www.survivorsuk.org/resource_articles/coping-with-disclosure/
There may also be local support groups available and I will say from my own experience that talking to other abuse survivors can be incredibly helpful.
I wish you and him all the best. Please do PM me if I can help any further.