Legal notice for husband as he is away from home from 2 months

I am married before 2 years. My husband and his family including his sister always abuse me and torture me for money and my salary. Hi father continuously reminds me that he married his son to me only for money and if I won't then better to get away from them . He also make bad comments about my appearance . My sister in law also interfere in my family life . Whenevr my mother in law came to me in these two years they assaulted me physically and mentally for money. My husband also do the this feb 2020 my in laws came to my house which I myself have purchased on my own they again quarreld with me for money and asked me to abort my chid my husband also forced me that he doesn't want this baby I was 7 month pregnant At that time. Now I have a baby of 6 months and my husband is not coming home form 2 months saying he wants divorce . Actually earlier I have seen some chatting and photos on his Mobile with some girls which was pointing to his affairs. I don't want divorce I want him to come back but he is not receiving my calls and not replying to my msgs. He doesn't want to take responsibility of me and my son. How could I send him legal notice to come back