I think your wanting to go away for a time (whether during the 10 days or otherwise) should be OK. We all need to get away sometimes; and I think your gut is telling you the truth. Do what you need to do to be well. He has a choice now to be helpful to you or not. If he told you the kid is not your problem, then he needs to back that up with behavior that confirms this statement. He is not doing that. (and, since the kid was a surprise, he really needs to be extra understanding; needs to understand this is Serious for you, and that right now, how you feel and what you need is Important) I wouldn't hesitate to let him know his actions now can, and likely will, determine if you can be there for him at all....
I am so sorry you are going through this.