Step dad hates us now

We have always gotten along pretty well with my moms new husband there’s been a lot we have over looked however because we know our mom is happy and we don’t want to come between that. We were recently invited to a bbq with our step dads family there were some older men there that were acting pretty inappropriate around my sister and I and saying some pretty rude things. We are adults but the men that were there are much older than us 40-50 ish. Anyways we have a pretty sick sense of humor most might consider nasty lol but we keep it to ourselves in a group chat on Facebook. Myself my 2 sisters and our brother are all a part of. The men that were there were being pretty gross touchy feely drunks and it was kind of getting annoying so we took a couple pictures of one of them and edited them with some funny stuff we put a penis on his head because he was being a dick and super ignorant. Wrote a couple things saying they were nasty etc. all of which was in the group chat we didn’t post it to any social media no one else saw it was all in our private group chat. Long story short it’s time to leave the barbecue we say thanks for your hospitality were super polite and we left. A few days later my mom asks for my younger sister‘s password to her Facebook because she wanted to look at a video. My mom had recently deleted her Facebook. The next morning my mom pulls all of us kids into a room and tells us that our stepdad went through the messages. Mind you to find these messages you would have to scroll way up in our group chat to find them now the house has tension so thick you could cut it with a knife. I feel like he should never have went in our group chat that was our personal business my mom is trying to get me to apologize to her husband and I don’t feel in the wrong.