You will always be depressed if you carry on behaving as if everything is fine. You cannot keep pushing down hurtful emotions and not expect it to affect you. If you do not deal with this you will have a total mental breakdown.
You need to speak to your GP to access therapies to help you to come to terms properly with your past. Push for this.
WWID?
Personally, (but I don't have depression so not sure if this is realistic) I think I would write emails or letters to my parents, calmly explaining what you have told us and more. I would explain that, irrespective of them preferring me not to feel negative about things, that I do.
Basically, I would pour my heart out and bare my soul as calmly as possible and explain how you felt and feel because of your experiences. You need to purge yourself of this pain to ever be free of depression.
I would write the facts - what happened and how it made me feel and why. I wouldn't allocate blame.
I would then not contact them. Leave them to contact you, which they will hopefully do, when then have had time to properly assimilate what you have said. Unless they are despicable parents rather than just misguided, they will want to to be happy. I think they do but don't want to admit the damage done to you by their decisions.
I know someone who never dealt with their abusive upbringing. It was too painful but it ended up causing a breakdown, many years later. They always put a smile on their face but they were damaged inside. That affected their children, just as your children will be affected by your depression.
If you deal with this now you can prevent your children from seeing you as a negative, depressed soul. They can learn that talking helps, that problems can be resolved and that people can choose to take action that can make them happy again. They can learn that communication is key to virtually every experience in life and the better they get at it, the happier their lives will be.
Please don't confine yourself to the life you are half living now.