It as was a nice gesture on your part, but you are not his mother! He's the one that screwed up and he needs to learn to bail himself out. You have to take care of you and your children now and any money that comes in now needs to be applied to your situation. I'm glad he borrowed from his friend.
The ow needs to step up to the plate and take care of her little boy now. Of course, we all know what she's after...good times and spending. I seriously doubt that she would help bail him out of a difficult time, i.e., she's expecting you to do that since you are his wife.
This is the hardest part of the journey...we cannot fix them, we cannot bail them out and above all else, we need to leave the "mothering at the door. They need to find a way to grow up and they cannot do it if we "moms" are there to assist them.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.