Mother in law and husband fighting about to have baby in 3 weeks!?

Ok so here is the situation in a nutshell. Hubby and I are expecting our baby in about 3 weeks. Right before i got pregnant they had a big fight (She was kind of a crappy mother when he was growing up) His last straw with her was about 2 years ago come august she had to serve 6 months for embezzlment (no judgements please, hubby is a great man!) We had to take in his 17 yr old sister to get her finished with highschool and that put our baby plans on hold bc we own a 2 bedroom house so we wouldnt have room for both baby and her. Anywho, we knew she had probably been stealing from her current employer and she swore up and down she didnt... WELL WELL she did and got caught and he was just so over her crap and drama and lies so he told her he was done and didnt want anything to do with her anymore.. he was mad. Well almost 9 months has gone by and he has stuck to his guns, i talked to her about once/twice a month to keep her up to date on her grand daughter and find out how my little sister in law is doing( although we DO talk to her.)He knows this and is ok with it,he is not totally heartless when it comes to his mother. his grandparents, aunt and uncle and little sister are coming up from LA when the baby is born to stay about a week and he has made it clear to them his mother is not welcome, his family understands and agrees bc its his baby and life so ultimaly his choice. I really want them to work their problems out but i am not going to cause a riff in my happy healthy marriage by pushing how i feel on him. I know she is heart broken that she has missed all this but it is her fault, she really was a bad mother to him and she knows it and will admit it. She has a problem with lying and stealing and he and i dont want that kind of person in our daughters life, but i am willing to let her be a part if she can promise to get some help. How do i get through to him to help him, i know he is hurting and this is about to be a phenominal time in our lives and i just wish they could work it out. She does try to contact him but he will not respond! please help this big preggo mommy.. i am at a loss!!!!