Here we go again

Well it is my hubby's b-day and the emotions I feel for him are sadness and anger.  In the past week he has went out and done Crack Cocaine  six time for reasons unknown to me..........  I DO NOT understand how the one person who has already watched, picked me up from being with another Crack addict can now do it me to himself.  I am so frusterated and do not even begin to know how to handle this situation, my first action is to leave file for a divorce and not look back, but obviously this is not first incident with this crap!  I have tryed to give him many chances to be there to help, but nothing I say or do makes a difference!  I am the one who has been told they have Cancer, I am the one who is taking care of her parents, taking care of our children, taking care of it all, everything but me...............  Everyone tells me you have to take care of you, but when----when he is out getting high and I don't know if I can count on him or even be able to get a hold of him----when my Dad or Mom needs me---or when my kids need me?  How could he do this me to us?  We have already been through a bad sitation with Cocaine several years ago and it ended with him serving 6 months in jail, and 3 years probation.  We have had a great marriage-a great realtionship for the last 3-4 years and then within the last 6 months now we are dealing with this.........  I have many health issues, but recently I was told I have Cancer!  It has been very scary for me but I haven't let on to that to anyone until recently.  I have sooooooooooooo much on my plate right now I don't even know how to begin to make things better and my biggest fear is what if something happens to me?  Who will take care of my babies????????????????????  I am so freaking mad at him and makes me want to beat him!  Plz I need to know what steps to take to get my husband back!