I am so sorry for your pain. Oh how I remember asking "why" so well. Sweetie, there is a much better life out there, free from addiction, insanity and hurt. You're so caught up in it that you can not see the forest thru the trees. We become so confused and cannot see the truth before our very eyes.
As painful as this, please try to understand that all your husband cares about is getting high. His brain has been hijacked. You cannot apply logic to addiction. For most of us, we will never understand the insanity of it all. And it would take many, many months, if not years, of very hard work for your husbands's brain to heal! Sadly, very few crack addicts break free from the hold it has on them.
Please start taking care of you and keep your previous baby safe.