Help??? - all advice welcomed & needed

I know this should be in a different group But you ladies are very blunt and honest which is what I need.

My SO had a very hard childhood, his biological parents were abusive and addicts and he got adopted at age 7. since his parents never sent him to school so he had a hard time catching up But he did and he graduated on time at the top of his class. since English isn't his first language he struggles but I willingly proofread his paperwork and read things to him,etc. I tell him how proud I am of him he went from being a 7 year old who wasn't even potty trained and knew 3 English words to being a supervisor in a predominantly white male dominated industry at 21 earning more than enough to live comfortably. But he still has really bad depression and esteem issues because of his childhood and how much he had to struggle. Some days he'll be happy then something will happen and he falls back into that pit and it can take almost a month sometimes to get him to talk to me again. I want to help him But I don't know how. Does anyone have advice? How can I get him to see how far he's come? how do I get him to understand that his past doesn't define him.? we're gonna have a baby next summer and I want him to see that this is his opportunity to do for our child what his family didn't do for him. I love him and I hate how sad he gets.