What to do?

Hi there, 

I'm new here. Trying to be short, I think that my boyfriend abuse drugs. Don't know what exactly as I found some pills without any marks. We live together for 4 years and were dating for 1 year. I love him, we plan a wedding. However, now I'm afraid of what I've found. I scare even to ask him about that. I start browsing and found much info on how to identify an addict. I read on https://addictionresource.com/drug-rehab/family-programs/ some advise that I need to talk to my husband but I cannot. I cannot even admit that he uses drugs. Whyy???? What is the reason??? Why do I know nothing??? Its hard, too hard to me.