Awwwwwwww......And yes - she's feeling he is hers. WHICH YOU WANT HER TO FEEL !!
I know you had a hard time with this but he will have a fun brother to play with and they came a long way just for YOUR puppy - how special is that ???
I bet he has a wonderful life - and she already has a Chi so you know she's experienced.
HUGS TO YOU MOM......I know I'd be crying too which is why I could NEVER breed.