Second baby after postnatal dep?

Before I had my first son my partner and i had decided that we would love a big family and so we got started on it! My son who was very much wanted and planned actually brought my whole world crashing down soon after his birth. I struggled with constant sobbing, strong fear of everything around me, halucinations and an over whelming desire to end my life (as well as the normal things like a healing csection, sleep deprivation and struggling to feed). After counselling anti depressents and cosntatntly reminding myself of the happy person i was before my sons birth i eventually came around. I look back at that time and its all very cloudy, people ask me how my son looked or acted as a new born and i honestly cant remember. I feel that im back to normal now but i still get very sad and feel inaduaquate anytime i think about his first year. My son is two now and my partner has started talking about us having another baby which has been on my mind allot lately too, happy and normal me cant wait to have another baby, loves pregnancy and finds it all so exciting but when i think about the illness that took over after i had my son i get very scared. I dont want to hold my whole life back and never have any children becuase of this but i am just so scared of it happening again or even relapsing as worse. Obvioulsy life with a probably 3yr old and a new born may even be harder than the first time? Has anyone ever had this or can you offer me any advice?