I've been where you are. I know it's really hard, but you need to talk to your parents about getting some help for this. If you aren't ready for that yet, there are tons of suicide hotlines that would be more than happy to help. 1-800-273-8255 is one of many hotlines in the US. Please get some help, any kind of help love! I know it's hard to believe right now, but suicide is not worth it, and while getting over depression is hard it's so much better than living in it.
So sorry to hear what you are going through. I've been in the same situation pretty much at the same age as you. My Real Dad also left when I was two. I am 25 now I can tell you from experience suicide is not worth it. I also had suicidal thoughts and even cut like you mentioned but I took it further and took a handful of pills not until I was older but I can tell you I am glad I didn't die. I thought real hard everytime I felt suicidal about my family and how I would cause them hurt if I ended my life way too soon. I don't want them to hurt and I didn't tell my Mom right when I was 13 either but I got help from a school therapist. She was so helpful. I loved having her to talk to. Eventually when I was in high school my Mom and I got closer and I was able to talk to her to. Are you and your Mom close I think you should definitely tell her how you are feeling so she can help you get help. I was put on medication for my depression/anxiety and was able to find the people who really care and will really help. Talking helps (: I'm very happy you had enough courage to post here that's a start!! My little sister is 13 like you and she's going through the same stuff her dad also left her young not quite as young as us but when she was around 4 or 5 but she still gets sad about it and she recently told my mom about her depression and cutting. I am so happy she confided in our Mom. Now she will get the help she needs, and It will help her to have our Mom to talk to, I wish I would of when I was 13. If you ever need someone to talk to feel free to write me. Let me know how you are doing..
hang in there kiddo. you are loved. you just need to either tell your mom or a counselor at school that you are going through a severe depression and they will find you the help you need.
sometimes when we are depressed we cannot see things the way they really are. our mind is our worst enemy. therapy and if necessary, medication will get you on the road to recovery.
make sure you insist on therapy and not just medication. peer based groups are wonderful. you would be stunned by the number of kids who feel exactly the same way you do.
help is out there, just ask. if one person doesn't listen, keep asking until someone does.