depression 5 months after giving birth

Am so ashamed to say that I think I have postnatal depression. My whole pregnancy I was in and out of hospital. & then since he’s been born it’s exactly the same. He has milk allergy ,serve refluxs , ulcer for 5 weeks which are under investigation. He never use to cry until the last 3 months and my marriage has gone down hill , I just cry as soon as baby goes to sleep and so scared to sleep Incase of ‘ sids’ and I’ve no idea why. Just before my pregnancy I just lost my Nanna & 2 uncles & my grandad. My dad got cancer for the second time but has got the all clear now . My mum has problems with her heart which is under investigation. My husband has aspergers adhd and Austim. Am just so struggling. My heart is broken yet so full of love I wouldn’t change my little boy for the world I just can’t explain the feeling I am feelingI and it’s just hit me like a ton. I managed to keep it away and to the back but finding it so hard right now.