I don’t want to breastfeed anymore

Short backstory: I have a one and a half year old and a one month old. I never got a break between breastfeeding my first and my second. My newborn has sever colic and between the two of them I am not getting any sleep. I’m uncomfortable and exhausted and I can’t get any help because she breastfeeds and I don’t respond to a pump. I am depressed and just over the whole thing. For my mental health I need to stop.

My question is what type of formula is best to transition her?

Please no judgement. My sanity and mental health is important for me to be a good mother.