You may have to consider getting someone professional to talk to the kids and for them to talk to if necessary. When you talk to them I think that you can be honest that you feel upset too. Hopefully they can still have a good relationship with Mr. Mind and hopefully he will step up to the plate as a father in whatever the new dynamic is.
You will go through a range of emotions, I'm sure. Make sure that you take time to feel them all and work them out of your system. It will take time. It is not an easy thing to deal with.
You are a strong person but sometimes strength deserts us and even strong people want someone to lean on. This is the time to use your suppport group. And then there's us !