Daughter in law and her family causing my mother health issue

Hi, I am writing this letter keeping my mother health in mind My brother got married 2 years ago and they are now blessed with a baby boy who completed 1 year now... First 3 months of marriage were good but after 3 months my brother got to know that she is having a kind of affair with her company owner. My brother took her phone and went through messages which were like (I love you, I can't leave with out you and don't worry i won't leave you what ever may happen) above are the messages sent from daughter in law to her boss. We enquired her and she was like there is nothing sort of those things, those messages are shared in a friendly manner. The same day we got to know that she is texting another guy too by saving his name as her sister name. Everything we discussed and she told that it won't repeate again and it will be stopped... Day by day goes and she was blessed with baby boy. Hence after delivery she went back to her home. After that there were some issues where she got very close with my mother's brother's wife and they became close sharing each and everything daily. Daughter in law got to know something that my mother has spoke something bad about her mother's brother's wife and she started behaving wrongly with my parents and my brother. For almost 9 months We as family had saw the baby for only 5-6 time in whole 9 months as she was denying when we come to visit the baby. Basically she didn't allow my parents so see the baby.We called her back home has she completed 9 months staying in her mother house. She came to our home but on the same day she started arguing with my parents. Has this was a baby of 9 months she didn't stop going to the job (same place where she had affair with boss) she told I will go to job and I will only go there. We thought ok that company is good for her because it was very linient and we allowed her. Morning while she was going to office my mother asked her how can we feed him, what and when should we feed him because we didn't know what routine have they made baby follow. When my mother asked this daughter in law said that if you don't know how to take care of baby then why did you bring us both here blah blah blah... At the same day night she behaved very wrongly with my brother and aggressively behaved to take baby which was holding by my brother. My seeing this my mother BP shooted high and she felt unconscious for more than 10 mins. Later on we took her to hospital in same condition but we got that reports that there is nothing wrong it happened just cuz BP was not in control. My mom is already a sugar and BP patient and by knowing all this daughter in law behaving the same way and now again she went back to her home. My brother who is helpless daily going to her home to see baby but my parents here in home are suffering as they are unable to get hold of their baby. In a month may be a 4 or 5 days my parents are able to see the baby as she only comes during weekend to our home with baby. My mom is 65+