Please help! My hubby wants me to invite another woman into our matrimonial bed

I’ve been married for a couple of years with a 17 months old baby. My husband has been pressuring me to invite another woman into our bedroom for a threesome to add spice to our sex life. Unfortunately we’ve two married friends who try this and he now wants us to add that element to our marriage. I’m interested in it after hearing of it from our friends who indulge inside but I’m not comfortable with going alongside it.When I asked among the women why she consented to it, she said she’d favour her man cheat facing her than behind her back like the majority of husbands do. I don’t want him to cheat on me at all but he keeps insisting with this and I don’t know how to talk him out of it. Should I agree? I don’t want him cheating on me.
Please help!