i'm so sorry to hear all that... life can be so hard.
as far as eating through your sadness, if it can help, try to say to yourself every time you go eat something as a comfort that it is not food you long for nor can it really help, it is actually only a way to punish yourself. and you are not to blame, life sometimes just takes a course not easy for us.
i ate my way through so many problems and it got me too far so all i can say is: when you're sad, cry, talk to someone, don't try to find a friend in food, you will only find more problems there.
good luck!