New baby, Troubled marriage

I'm a stay home mom of one. He's 4 months old and I love him so much. I suffer from postpartum depression. Most days I hate the thought of even getting out of bed. My life revolves around him and I'm beyond tired. So when my husband gets home he usually takes baby and gives me a break. I appreciate him for that but our relationship is suffering badly. He leaves home for work at 5:30 am and gets home around 5:30 pm. So naturally when he gets home he's exhausted. He eats and then takes a bath then gets the baby. During this time I wash dishes from dinner then get ready for bed. We do bath time with baby together and put him down around 8:00 or 8:30. By then we're both exhausted and stay up until around 9:30 then go to bed. We maybe spend an hour together out of the day. I don't know how to revive our relationship. I want the old us back. What do I do about this