You say that at times you feel obligated to go through this, why? What did you do to deserve to be saddled with all that debt? Those weren't your decisions. Life is hard enough for all of us, there is never a reason to take on the burden of someone else's folly. That's for him to carry.
There are two problems here. Not only has he extensive debt that will cause him to be completely unable to contribute anything economically to your future with him, he also hasn't been very upfront with you.
It appears that he has disclosed his debt in pieces to you, leaving you with another surprise to learn as you get to know him more. Whatever other surprises await you once you are tied to him? He also apparently believes that you are his economic lifeline and will thus pick up where he can't financially.
I'd back out of this one. He needs to see a credit counselor immediately. They can help to negotiate with the credit card companies on his behalf for lower or no interest and work with his other creditors as well. They will also make him get his head on straight about how he makes financial decisions.
Possibly if you want to wait to see if there's hope, you can tell him no go for now and that he needs to see a credit counselor. Go with him to the first few appointments to see if there is hope for him to have his debt manageable in a year or two.
His ability to follow through with their program will indicate to you if he's mature enough to be a good mate for you. Also, you will need some objective opinion as to his prospect of future stability and how long down the road that is.
Or you could chose to forgo all this and scrap the relationship at this point. Its entirely up to you and how much time you want to invest with this guy. One thing for sure, I would recommend not committing to him in anyway until he makes an effort to put himself back on track.