Note : do NOT say "it's over" or "we are done" or any of that nonsense. Just tell him infidelity is toxic to you and the children. Until he leaves that OUT of the family and marriage he needs to keep away from the family home.
No grandiose "we are through" or any of that. Just tell him to leave.
Once he's out, and you have your wits about you, then you can organize and plan for long term.
Do NOT say ANYTHING else. Just tell him to leave before this gets violent. Tell him this is HIS toxicity he brought in, and until that ENDS that HE must be GONE.
YOU END the conversation. Do NOT allow him to drag you into an argument.
