I'm sorry to hear you are going through this, especially now
I'd have to agree with the ladies. You need to do what is best for you. You can talk to people, try to get opinions, to help you decide, but... the bottom line is, no one knows the full story exept for you and him. So the bottom line is you have to figure out what is best for you and Mikayla. It's hard, the descision hurts, at times, all the options seem wrong, seek counsel from friends and family, but only you know what is best for the two of you. It is very nice of you to be concerned about his son, but right now, you need to concentrate on You and your daughter. We can't save the world, but if everyone does their part, the world will be a great place. Don't be affraid to do what you need to, it is important for you to have a happy healthy environment for you and your daughter.
I can't believe what he said, insensitive, or just dumb.

Don't be affraid, once you've made your final descision, you will realize it was the right one, and things will become easier.

Stay Strong, take care