Overwhelmed parents

My LO is about 2 months old now and he's my first baby. Currently my mil helps taking care of my LO, after my confinement. She will look after my LO during day time so that I can get some sleep as I would stay up all night to care for my LO. There were many instances where I witnessed her carrying LO the wrong way and almost got a heart attack (carrying by the armpits/with one hand on LO's neck and leaving buttocks unsupported as she would be doing tasks like feeding and grabbing towel with another hand/pressing LO's head down when he's struggling and crying out of discomfort and etc). Despite reminding her of the danger and consequences of such actions to a young baby she would still forget and do it sometimes. Nothing seems to be going right especially when she is not able to put my LO to sleep and cant comfort him when he cries out loud, misread his hunger cues and etc. My LO is also a light sleeper and gets startled easily and she doesn't seem to be considerate enough to be quiet during his sleep time by talking and doing things loudly. I have no peace - can't help thinking that my LO is in lousy hands. I'm extremely worried about the safety and well being of my LO. I'm mentally exhausted, sleep deprived, physically in pain, stressed out and frustrated with my MIL. My husband is well aware of what's happening and he's as worried and stressed out as me. He tries to help whenever he's able or back from work. He communicates with my MIL everyday to remind her of the Dos and Donts. I'm lost here and don't know what to do. Most of the days I would be awake to tend to my LO during day time because my MIL can't seem to settle my LO when he cries. I sleep only 1-2 hrs per day although she's "supposed" to help out during the day time. I'm grateful for her wilingness to help but at the same time I am extremely worried. If i could i would tc of my LO all day and night but due to my extreme back and hip pain, I'm not able to. My husband is suggesting to hire a day time nanny to help with the situation. Not sure if it is worth the money and is it a wise move (do not want to hurt my MIL's feelings)? Any advice please. Greatly appreciate it.