Don't Know What To Do

I belong to a country where talking about sex is taboo. I fell in love with amazing person and got married to him . I really love him a lot and sex life is great with him it just not as great as it used to be before marriage. So these days as I was not getting time with him I became horny like hell and suddenly I got the urge to have sex with another person except my husband . I have never felt anyonelse . He was my first man and till now the last. So basically my friend offered me to have sex with him I so damn badly to feel someonelse to know the different experience but the problem is my guilt . I can't cheat I keep telling it would be the first and last time but it makes me feel guilty.
So shall I go for it as I never felt anyonelse