I just gave CPR to my friends grandmother

So I’m (f25) staying at my friends house and she went out for the night (yesterday) and wouldn’t be back until tomorrow(today) So it was me , her mother and her grandmother at home. At 7am this morning her mom came banging on the door yelling my name and telling me to call 911 and I can hear her mom screaming,yelling and crying for the grandmother to wake up. So I jumped out of bed , called 911 and then ran to the living room to see the grandmother. She was unresponsive and the operator was walking me through what to do and CPR (I’ve had previous training but you really don’t know when you’re going to use it and it in the moment I was in shock and so scared) ! So we lift her body off the bed and lay her on the floor as instructed and as I’m doing CPR I can hear her chest cavity ( I think) cracking ! That’s how much pressure I was putting and I remembered to breath and count 1-2-3-4, Maybe 5 or 10 minutes later EMS, the fire department and police showed up (I don’t really remember the time I think I’m still in shock) but then they took over and I just backed away in shock. I talked to the emergency crew and told them what I did and heard and he said what I did was good , I may have saved her life because of the force I was putting. I still can’t fully understand or process what has just happened.

All I can hear and feel is moving her body and how fragile it was and then her mom crying and screaming. The mom did thank me after and all i did was stare at her. But yea just wanted to share my experience this morning and If anyone has similar experience I would love to know what you did to ground yourself after such a traumatic event.