Don't blame yourself. Breaking up with a long time boyfriend is hard. It's worse when that person lives in the same house. Will he be moving out ? If he has to stay for financial reasons, then you should try thinking of him like you would a college room mate. He's just sharing the space, nothing more. It'll be tough to make the emotional break, but once you do, you'll start feeling better. letting go will take time.
Quitting smoking is just as harder if not harder for some people. You're probably feeling more than a little overwhelmed. Don't beat yourself up because things may seem like they are falling apart. You can get your life back in order, but you have to set some priorities. Don't try to do everything at once.
Set some simple goals. Quitting smoking cold turkey is NOT easy. So, why not try to cut back for the time being ? If you smoke 1-2 cigarettes a day, that would be a big improvement over a pack a day. You may find weening yourself off is less stressful than going cold turkey.
Have you joined any of the Spark teams for members trying to quit ? If not, I'm going to encourage you to join one so that you have the support of other members trying to quit too. www.sparkpeople.com/myspark/groups_individ
Take things one day at a time. Don't try to do everything at once or you will end up frustrated.