I'm glad your trip was a huge success and that you and your son had a blast. Disneyland will always be my favorite of the Disney amusement parks, after all...it's the original.

Now, about your h telling you about his sister, etc., I hope you don't get roped into that one. Her parents should be the ones stepping up to the plate to help her out, or better yet, your h now has a place of his own and plenty of space...he can have her come there and stay. She could be a great help to him...but your home is not the "mission for lost souls".
Quite frankly, his family is nuts to even think you'd take them in. After all, you just had one man/child leave to find himself.

I am sure your fur babies were happy to see you and your son. Enjoy your weekend.

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.