Sorry to hear about all the issues going on. If you have a really immediate issue you may want to seek professional help.
As far as your self esteem. I lived the first 18 years of my life mostly down on myself especially when in social situations at school. The thing that dug me out of that hole of self doubt and depression was finding a passion. Not to be cheesy, but finding something that was all mine. I liked watching magic shows, reading about magic history. That interest led to a career I still have. Another example was building remote control trucks. It really benefited no one else except myself. I got the pleasure of building something from a pile of parts.
Anything that interests you that you do purely for yourself will build up your self esteem that you are more than a girlfriend and mother. You are a unique human being. When you explore your own life apart from the issues going on in life you have a safe haven to retreat to for you to find peace and strength.
Reading positive books "Gifts Of Imperfection" by Brene Brown is a good one finding friends or making new ones who are positive. My number one suggestion for what got me out of despair was in attaching onto something that interested me and getting involved with others who had that same interest.
Doesn't have to be a deep passion, just a simple curiosity about a subject or certain thing and exploring it. Enjoy each experience of life and learn that you can control what you experience no matter what others do around you.
Again sorry for your tough situation. Hope these thoughts help inspire you and I am sending good thoughts your way! I know you have a lot more to offer than being a mom or girlfriend you are a person first.