Divorce or Maintenance ?

Hi, I was in a 17 years of turbulent marriage with domestic violence with physical, verbal, emotional and economic abuse as a result I went into acute depression for around 10 years without knowing. Attempted suicide numerous times in past but after treatment for depression I'm stable. My husband have been cheating upon me in past but I couldn't come to know.. recently I happen to see his mms with a girl over a video call and both were in compromised situation and enjoying act. This has created a fresh mental trauma on me and I couldn't expect what all happened to me in past regarding abuse and cheating. We had a love marriage. We have a son 15 years of age. If his ego is hurt he starts economic abuse and we find it difficult to survive as I'm not financially dependent. Now my husband has moved out of house since 6 months over an argument and mentally harassing me over emails and phone. I don't know how to solve this whether to go for divorce or just ask for maintenance. He also threatens me of leaving his job if I ask for more maintenance than he wishes to give. He's at a reasonable high salary package but don't want to give anything to me. What can be the amount of maintenance that I could ask for without divorce or if he actually leaves his job and we are left with no option then what to do.. kindly help..