New Moms Sadness

hey ladies, so for those of you who are new moms or remember this phase well, i am 4 days post partum, and took a shower in my own home for the first time and sobbed the whole time. it hit me like a train that the last time i was in that shower i was with my fiancé and it was just us and life was easy and we could stay up or go to bed early or wake up late and bring our dog in bed in the mornings….and now i feel so lost. like my fiancé is so close but so far and my identity is now to be a mom and keep my baby from crying. feeling like this has caused so much guilt and makes me feel like a terrible mother already for having regret about this decision to start a family.