I don't know what to do. I hate feeling like this?

I'll just get straight to the point. My mom died 4 years ago, and I was fine back then, but some reason I'm not now. I literally cry at least 3 or 4 nights out of every week thinking about it lately. Mother's Day and the days leading up to it were the worst. I hate hearing all of the hype and seeing all of the merchandise in the stores. I just want to see her again, and that's obviously not going to happen. I don't know what to do. I feel like my heart is completely broken, like I can literally feel a pain in my chest when I cry sometimes. I'm an all-A student and I think I may have blown the exam I took today because I just couldn't get myself to study because I was just too sad with all the Mother's Day hype the past couple of days. All of the suggestions to remember good times and write letters to her and stuff just make it worse, as do the suggestions to go visit her at her grave because I don't think she even has a grave. I don't know what was done with her--I know she was cremated, but I don't even know where the ashes went. Anyone know what I can do to stop feeling like this?