Will he really leave me if I do drugs?

I used to do drugs very heavily ever since grade 7. I've done pretty much the common known things like weed shrooms acid ecstasy coke prescription drugs and so forth.

My boyfriend knows this and he said if I ever did another drug he would leave me and wouldn't be able to be there for me.

All my friends try and say that its a dumb reason to stop but I need to for him. How to I reasure him I won't do any and than tell myself I don't need too. I grew up in the best household so I don't know why I turned out like this :(
Will he really leave me if I do drugs?
Post Opinion