You can't trust him no matter what he tells you. That's what it comes down to. No, they don't care if it hurts you. No, they don't care if it negatively impacts the children. They do what they want, when they want and with whom they want. That's all that matters to them.
Also, stop having sex with him. It's not helping your situation and you are exposing yourself to possibly catching an STD every time. The truth can hurt, but it can also heal.
"Some of us don't see people how they are, but how we need them to be".....quote from Uncertainone