Hiding Depression

I'm still really messed up and extremely depressed at how things played out with my child's father and I...after dating 7yrs, losing our son , then me giving birth to our daughter I found out he had been messing around ( I know I know I deserve better his lost blah blah) but I'm the one currently struggling with getting over it... I wanted my family. Anywho I guess it's starting to weigh on me physically because he is always pointing out things 
-I've bit my nails down to the quick I can't help it 
- I've lost 20 lbs unwanted so all my clothing fit bad 
- He always ask why I look so sad (I try to put on a happy face I guess I'm not doin a good job) 
Those are all things I've noticed about myself but I didn't tell a soul and he points it out right away 
How can I hide it better.