I cheated on him and I dont know if I should tell him

I know its horrible and I've been beyond stupid and me being drunk is not an excuse but I love him so much and I dont want to hurt him.
His ex girlfriend cheated on him twice he was so broken and he trusted me so much I can't believe I really did that.
He's not the problem at all its not our sex life either he's actually very good maybe the best I've ever had sex with but I dont know why I did that I regret it so much.
I know I have to tell him I love him so much but how do I tell him?? Please dont be too hard on me I know I fucked up badly but I really need some advice.