Feeling so sad :(

My baby boy is 1 wk 1 day. Since we came home from the hospital I've had days where I'm sad and all I want to do is cry. Then other days I'm ok. I am breastfeeding which is taking a huge toll on me as I'm not sleeping much and the stress of knowing I'm the only one that can feed my baby is too much. I dread night time because they're so long and tiresome. When he cries I begin to get anxious because only I can make it stop. My fiancé is helping as much as he can but I'm almost jealous at how little the birth has seemed to affect him as much as it has me. He's been great but I'm struggling to want to keep breastfeeding. He just wants me to be happy and I try telling him I'm not sure what to do either! And the thought of him going back to work next week and me being here alone terrifies me. Ugh! I just thought I'd be so much happier.