peace- I am so sorry about your S's asthma. My S has had allergy induced asthma too but hasn't had any flare ups for the last several years (we are hoping he is now in "remission")...it can be scary if they can't get it under control...especially to the point that you are considering taking him to the ER. I can only imagine the stress this has caused you especially when your H won't help. Has your S seen a pulmonologist? Has he been put on any medications to prevent the flare ups?
I have heard that asthma attacks can also be brought on by emotions...not sure if that is a fact but regardless, you are doing the right thing by trying to keep your S from know that his father can't handle things.
I am sorry that your H just can't seem to deal with much of anything. If only he would recongize that he needs some help. He will eventually realize how unfair it was to burden you with everything. Someday he is going to figure out how screwed up he was...just who know where you will be by then.
I hope your S is okay. Stay strong. Your kids need you so much.