I think I'am going into depression..?

I had a huge fight with my mom two weeks ago regarding my career,then I fought again in the night. But when she told me I am free to go if i dont want to pursue what she thinks is best for me,I lost control of my temper and left. I left the house. I neither took my phone with me,nor took any money. I had absolutely nothing with me. My father tried to stop me,but I didn't stop. I don't remember how far I went,but unfortunately,after an hour or so,my aunt saw me and took me back to my house. We met my father on the way back and he had chest pain. It felt like an attack but he took some meds immediately and he as fine. One week later,he had a heart attack. And I feel I triggered that attack. I can't help but blame myself for it. From that time,I've just been trying to make it up for them. I stayed with him in the hospital and I'am nursing him 24x7 now. I don't know whether I'am doing it out of guilt or out of love and care for him. I curse myself and cry every night. Till then it was just me blaming myself. But two nights ago,when my sisters literally blamed me and asked me if i want his health to deteriorate further,I felt soo horrible. I just couldn't stop the tears(when i was alone,not in front of them). I hate myself! I can't look myself in the mirror! I don't know how far i'am responsible for it,but its just killing me. It's natural for others to blame me,I don't object to that.But how do I react? How can I cope with the depression? Nothing makes me feel better. Please help.