Good solution for a good relationship as mother threatens to die

Hi,

Good afternoon I belong to a middle class family we are 3 sisters and from childhood we grown up with very difficulties as my father is a drunken person he use to and now also harasses mom and us and grandmother use to help us in financial matters. I never thought of fell in love with someone but unfortunately I fell in love. I'm in love with one person from last 4yearst but due to some issues he scolded my sis and mother 1yr back bcz of me only so mom and sis don’t like him and he belongs to some other caste so mom searched 1 match for me I said I will marry my boyfriend only then she started crying and her health is also not good so I said my boyfriend to speak with my mom he came to home and spoken to mom but mom said no. Then I said mom that I will not marry him without your permission and if not him I cannot marry anyone. Then mom said that she will die if I will not agree for marriage with someone.

Please advise me the good suggestion for a good relation ship