i messed up

I used to drink a lot a few days back. I couldn't cope with how I felt and buried myself into alcohol. My boyfriend has a past with substances. It isn't a good past either. So I learned that when I started showing up tipsy he was very uncomfortable with me. I feel horrible that I hurt him in such a way, especially because alcohol or drunk people make him possibly relive the past. I dont want that. We're talking right now and I promised to be better for him and apologised. But I have no clue how. I am cutting everything off cold turkey, that is easy for me. I don't understand how I am supposed to fix this though. I don't want to hurt him more. I feel so shitty and I deserve to feel like that after what I have done. Please offer advice and tips for this and how to talk things out, and is it bad to say that I love him in an apology?

Thank you