How do you go through a break up when you're practically married and have investments together such as a house and car and the other person has let their life fall apart?

You loved this guy once and if you think marriage is a bowl of cherries think again. If you are going to fall apart over this problem, then you wouldn't be able to handle other problems in the marriage. People shouldn't be so smug, because it could be you with a problem in this relationship one day. The best thing to do is have a talk with him and separate for a period of time. Make sure you let him know if he's not going to go for help (you'll back him 100%) and won't even try then the marriage is off! Then go and see a lawyer. It isn't wise to get into investments of any sort when just going with someone and this is something you should save for marriage. If lucky, your lawyer may be able to get you out of this mess.