trouble gaining weight

When there is stress in my life, especially relationship stress (currently separated from husband, his choice) I completely lose my appetite. I’m a thin person to begin with and I’ve lost 20 pounds I didn’t need to lose over the past 6 weeks. Food does not appeal, it does not taste good, I literally have to force myself to eat. I’m not OK with how I look, it doesn’t feel good to me to be so thin. I’m a very healthy eater usually so when I do eat, I eat well. I’m trying to force myself to consume 1500-2000 calories a day to gain back weight but have only been able to manage 500-1200 so I’m not making any headway. I’m wondering how to Model this… Thanks!