Religion and diving in

So I'm Christian and my husband's catholic. We've been with each other since high school, and had only been with each other up until a few months ago. We met him at a hotel and we did a 3way, with my husband and the other man being bi curious, it really pushed us into unknown territory. The experience was great, I felt wanted and respected. It kinda went by fast from me being so nervous. But it was a successful interaction. Anyway, we've talked about doing something similar again and I'm so aprihensize! Idk if how sensitive I am or my religious morals but I feel like I'd be doing something wrong still. We both talk about our wants and what we like, but there is something stopping me from trying it again. I think morally it's hard for me to not think I am stepping outside my marriage or committing adultry. I'm afraid I'm just taking my desires and doing something that's a sin... even though I know we are not betraying our vows what's so ever. It's so hard for me to tell myself that I shouldn't feel ashamed of myself.

Has anyone else felt like this? What helped you believe you were being faithful still to your marriage and that it's okay to have these desires for other men? I love my husband so much and I know if I never get comfortable, it's alright just being a fantasty. But I know in my mind it's something that exploring together will bring us a better understanding and help us be ourselves fully. But in my heart, I'm so afraid still everytime we do it, that it will be a mistake.