Petya,
God bless you and guide you through this. Try to take things one step at a time and not second-guess yourself about your pregnancy. My husband of 15 years has not been good to me, but I have a 4 year old son with him named Kenny who I just love more than anything! What may have seemed like a bad decision at the time turned out to be one of the biggest blessings of my life - for me, and for my 19 year old son who has disabilities. Your older boy will love this baby, too, and also be blessed because he/she is here.
There is a saying, to try and "bloom where you are planted." Take things one day at a time, try to do the best you can for that day whatever the circumstances are. See if you can get yourself established with some help, and then gradually see where things take you. If you are in danger, respond accordingly. You are in my prayers. I just had to respond to you. I can relate to alot of it.
C.