My 4 year old son died of cancer and I am utterly devastated...

I’m a 36 year old single dad and my 4 year old son passed away recently after spending a long time in the hospital fighting cancer, specifically Leukemia. I still can’t fully process the fact that he’s gone. My entire life revolved around him and now the house is completely silent. Everywhere I look reminds me of him. My abusive ex-wife isn't in the picture, I lost my parents years ago, I don’t have siblings, and I don’t really have a large extended family. I have a couple of friends who reached out and were kind enough to send condolences, but they have their own families and lives and I feel guilty constantly unloading this level of grief onto them. I’ve taken time off work because I can barely think straight right now. I wake up feeling sick to my stomach and then spend most of the day either crying, staring at the wall, or thinking about how much my baby must have suffered. I honestly don’t know what I’m supposed to do now. Some people say things like "take it one day at a time" but the days feel unbearable and empty. I feel completely alone and like the future just disappeared overnight. If anyone here has gone through losing a child or something close to this level of grief, how did you survive it? What am I actually supposed to do with myself right now?