I hooked up with the love of my life on my best friends bed
Are you going to tell your best friend you had sex on their bed?
Noooo. I don't think he needs to know.
Then you should not tell them and keep it a secret. What they don't know won't hurt them. Would they mind if you lied?
It doesn't matter because they never had sex in their bed.
If you know this then you are a genius! I would just leave the bed to them next time, and try to make amends somehow even if they don't know about you and your sexual liasions.