Is masturbation a sin? Feeling so guilty 😞

I’ve always heard that masturbation is evil and that watching porn is another way to bring lust and sin into your life…since I’ve tried masturbation I fell so good with myself but I can’t help to feel so guilty afterwards. I did grow up religious and I know I’m doing something I shouldn’t be. I have a husband now and I

can’t help to think it’s almost like cheating on him.

Any advice? I feel so guilty..how can I stop doing this now that I’ve tried it? I have been doing it for twice every month now even after I tried to stop 😞