Dad on drugs

I just found out that my dad was doing drugs again, it's really not shocking because he's been off and on using drugs since I was little (for 17 years) Anyways it just makes me so mad because as long as I've been alive he's put the drugs before me. Now I'm almost an adult and I also have my own child, and I honestly feel like cutting him completely out of my life (since he's really never here anyways) but I still feel bad for thinking that about my dad. It's not just about me anymore though, it's about my child now too and I don't want him around someone who does drugs plus he already has a dead beat dad, he doesn't need a deadbeat grandfather too. He's never been here for me like a parent should be, but he's there for his other children. I wish I could just type out every single thing he's done and every single thing I'm feeling, but if I did that I'd be typing all night.😒