u/Winter_Low_5255

My (F25) dad (M58) and my mom (F58) have never had the best relationship, but they stayed together while us kids were growing up. They didn't fight a lot, but it was clear they weren't in love. About 1.5 years ago it came out that my dad was cheating on my mom. He had a secret bank account that he was putting tens of thousands of dollars to pay for escorts, who were much younger than him. My mom found out because he ordered a gift for one of these women using the wrong credit card. My dad says he hadn't had sex with my mom in many years and claims that this and being lonely is why he cheated, but admits he should have broken things off instead of cheating. My mom is still very angry and talks shit about him regularly. My dad has also been kind of a jerk to my siblings since the divorce. E.g. getting mad if they use his insurance to get glasses, getting mad if he gets sent a toll because their car is registered in his name.

I have always been closer to my mom, but my dad was never a bad father, just less involved than my mom. After the divorce I sided with my mom given the situation. She doesn't have as much family/friends nearby after moving after the divorce, so I've spent holidays and time with her instead of my dad.

I decided to get married this year even though I know things are still awkward with the divorce. I've been dating my fiance for 8 years now, so I didn't want to wait longer.

I knew this would be the first wedding my parents go to since their divorce, and unfortunately every decision seems to be impacted by that. When it came time to decide who was walking me down the aisle, I was conflicted on what to do. If I picked my dad, it would be hurtful to my mom since he just cheated on her breaking their marriage vows. If I picked my mom it would be like I was replacing my dad with my mom. I was honestly considering having no one walk me down, but everyone I talked to thought that was a bad idea.

I ended up deciding to ask my grandpa to do it. He's 82 and I'm the first of his grandkids to get married. He was happily married to my grandma for decades before she died. He stood by her through cancer and the death of a child. He's always been someone I admired for his commitment and love towards his spouse. And when I told him I got engaged he was so excited for me.

I thought this was the best choice since it would avoid choosing between my parents. I also just felt like he deserves to be honored in my wedding.

But I told my dad the other day that he wasn't going to be walking me down the aisle and he was upset. I felt kind of guilty, but I also kind of feel like he did this to himself. If I let him do it, I would feel even more guilty to my mom...

So, I'm looking for some objective opinions on whether I am the asshole here or not.

Thanks in advance!

Edit: My grandpa is my mom's dad. (I never met my dads parents and they are deceased) My dad is paying for about half the wedding and my mom for the other half.