Instead of metal handcuffs, which can be very uncomfortable if not downright painful, get some leather cuffs and a blindfold. Tie him to the bed, straddle his face in a sixty nine position and while he is pleasuring you with his mouth, tell him about the man you just had sex with. Get into the fantasy and be as descriptive as possible about the man's physique, the size of his cock and all the dirty things the two of you did together while you masturbate your husband.
About the point at which you get to describing the huge load of cum that your lover shot into your cunt for your husband to lick clean, he should be spraying his own all over his stomach.
You can always lick a little up and give him a nice big kiss to top it off.
The strap-on is good as well, but get 2 dildos for it, one white or other color than black to use on him and one black one for him to use on you. This way you don't mix them up and inadvertently cross contaminate each others orifices. You REALLY don't want his anal germs in your vagina. Trust me. Use condoms on them to make clean up easier as well. Make sure he is into being ass fucked before you try going there. That could be a hard limit.
Try to get one that fits right against your clit.
New fantasies: have him wear the strap-on and talk to him about how wonderful his big black cock feels and how your husband would go crazy if he knew you were fucking a hot black stud in his own bed. Play it up, but let him take off the dildo and fuck you with his own dick before he messes up the sheets.
Second: blind fold and cuff him and tell him about how your lover wants you to break him in and open his ass up for him to fuck while you give him a go with the strap-on.
That should be enough to help you get started.
Good luck and have fun.