Lost my mum to copd a month ago

I was a carer for my mum with copd for 8 years, she died on the 11th of January and I feel so lost without her, during my mums last week she was complaining of thumping in her ears like her heartbeat and she was dizzy when she stood up called the ambulance and they said it sounded like tinnitus a week went on and she didn’t sleep for 7 days, on the Sunday I came home from work and she was sitting up in bed eyes watery made her some breakfast heard her go to the bathroom and back to her room and she called me, she was sitting on the edge of her bed gasping she told me to call an ambulance and then her head collapsed in to the pillows head down and then She started responding again while I was on the phone,they took her sats and they were low and very low on movement, she went to the hospital and they called me that evening and told me she wasn’t getting any better on the ventilator, next morning I got a call that I should go see my mum because she declined overnight, while sitting next to her I held her hand doctors told me there was nothing more they could do for her. Chapel guy came in said a prayer then left then my mum opened her eyes a little at me then started passing away I called the doctor and she said looks like my mums last breaths I got up and panicked and left because I didn’t want to see her suffer, she was announced dead 1 hour 30 mins after I left which I regret and will have to live with for the rest of my life I feel so guilty for not staying with my mum till the end :