I am so sorry to hear about your loss and amazed at the strength you've shown so far. I also want to echo the people who have said how important it is that you don't second guess yourself and wonder if you could have done something else. You couldn't. Depression is an illness as real and deadly as any physical ailment.

I know the pain seems unbearable and at this stage all you can do is try all you can to get through the next day. Mourn and grieve in your own way and don't worry if it doesn't seem like you're going through the "right" stages or if you're on the "right" timeline. Eventually, the pain will lessen and it will be easier to focus on the good things about the time you shared.

I don't know you in person, but I hope you know how much support you have here and I hope you come and share your thoughts whenever you feel it would be helpful.