I am little bit surprised with this. Life is not a bed of roses. It is a mixture of all kind of experiences. Some time bad sometime good. Bad experiences does not mean that we have get rid of life. Life is very precious. We don’t know how we get this human life. So please remove the idea of suicide from your mind. After reading your question I was thinking about your love. Is it so weak that after 4 months of marriage you both have started thinking about suicide?
See after marriage life got changed too much. Before marriage you both meet each other for less time in a day. In that time you have no responsibility. So life was just like a dream. Now after marriage this situation is different.
Keep yourself in place of your mother in law. She is little bit scared of loosing her son. At the time of marriage she was not happy after knowing affair for her son and as you said that your husband has forced her to accept you. So she is feeling insecure. This feelings will take time to go. So I suggest you not to think in negative direction. You need to do some extra efforts to convince your mother in law that you are respecting her.
As soon as your relation with mother in law improve you will see a change in your husband behavior. Try to avoid arguments, anger and other negative feelings with your in-laws and with your husband. Also try to avoid foolish behavior of your mother in law. These are childish things and if they behave like this then ignore it. Silence patience and humble are the qualities of human. So make it your habit. As time will pass you will see changes.
If you take tension and start arguing with your husband then you as well as your husband will behave like this.
Please let me know your thoughts..