Should I talk to my mom about my dad being on drugs?

When I was 12 my parents divorced and I was never given an explanation as to why. After they were divorced my dad disappeared and I never really saw him ever. So when I was 17 my parents got back together (again nothing was really discussed with me) I am now 20 and recently I was on my moms phone and noticed a message from my grandma (dads mom) so I read it and it was messages insinuating that my dad was/is on drugs. I have no idea how I'm barely finding this out but it's really bothering me and I'm scared to confront my mom about it. I want to talk to her and ask for the truth because I think I deserve it but I'm scared... help please

I think you're old enough to be able to handle the truth. I do think you deserve an explanation. But as a mother, I have to say that I'm sure your mom has no idea how to broach this topic with you. For example, I eventually have to tell my daughter (she's 4) that her Daddy isn't her biological father. What age is the right age? Will she understand? Will she be upset? Will she want to know her "sperm donor"? Etc. So you can imagine your mom has probably asked herself 100 questions about whether to tell you, how to tell you, when to tell you, etc.

Since you've found out on your own, I would write your mom a short letter. Explain what you've discovered, how you feel like you deserve more of an explanation, and try to be supportive of her too ("I'm sorry you've had to go through all of this with dad"). Let her read it alone, give her the opportunity to gather her thoughts and prepare for a very difficult conversation with you. Meanwhile, prepare yourself for seeing your father in a totally different way.

I think at this point, the curiosity may be worse than learning the truth. I'm sorry you're in this situation. I hope you get the answers you need.