What is the solution for Sadistic behavior of wife

dear sir, I am hindu , Got married to a lady who lost her husband. I take care of her and her kid. But after marriage I came to know that , she is suffering from STD’s . Spent lot of money towards treatment , but she never take medicines in time. Many times I also suffer with infections , so that leads me to unsatisfied married life. Other part is she always talks about death , 3 times she did suicide attempts . she is telling that she is doing it to control me. But I don’t think it is the way to control. Now a days she s telling that she will put poison in my food. I fed up with her behavior , she always suspects that I have illegal contacts with other women. She don’t allow me to meet my parents , my friends , and my relatives. We did all the meetings with family people , but in front of all the people she talks very nice , once they left , she starts her sadistic behavior . now a days it is affecting my career as well as my health. suggest me what i can do?? thanks in advance.