Struggling

this is a great idea.

I'll just be straight out with it, it's my mother she's cheated on my Dad for years multiple people before they were married and after. She came to me one day a mess and I genuinely thought someone had died she was inconsolable, and of course my reaction was to try and help her and comfort her and then she started telling me about the times she has cheated on my Dad. I was in utter shock and in the moment I wanted to scream at her and my heart broke because I'm extremely close to my dad he is my idol my best friend. He is an incredible human and I see him and speak to him often and it kills me to be around him because he does not deserve this shit he has done nothing but support her for 31 years and I don't understand how the fuck she could do this to him. I was her release from her guilt and now I live with it in complete agony every single day. I have alot of problems with my mum and she's the kind of person that has never apologised when she's in the wrong and if I approach her about this she will deny our conversation ever took place. I don't know what to do because it will crush him and I don't know what he will do and that terrifies me in the sense that it will break him. I'm seeking professional help but I live with such guilt all day everyday.. I need others opinions do I break up a 31 year marriage. Will my Dad hate me for not telling him I'm so so scared and mentally I'm fucked up. I'm also like should I take this to the grave and spare my dad the pain. I feel like I'll be the blame for a broken family.

It's so messed up, I know it hasn't happened in years but why do it? And why put your only daughter through this, she could of used anyone else like a counsellor or priest a mental health hotline. The weight of this in unbearable and I can't lie it's not who I am I'm already an anxiety ridden mess, to me my anxiety feels like a death sentence. My mum has been hell for my dad for over 10 years and I can see he is at his breaking point. But I also know he loves her, I looked up to their marriage as a young kid and thought this is what I want and growing up and seeing the damage and its built on lies on her behalf I know this because she's been caught out in lies. Before I knew about this I told my dad to get a divorce and should of when myself and my siblings were kids would of been better off but it's not the man he is. My Dad not long after meeting my mum he rang his mum and said mum I found the girl I'm going to marry how bloody sweet is that, and it breaks my heart going back through memories I have suppressed because to open that jar for too long I'll end up in a mental institution. It goes so much deeper than What I've spoken about but this tipped me over the edge

To bury the secret I feel like I'm betraying him and the love I have for him feels wrong because I'm keeping locked away but at the same time he doesn't deserve the pain and betrayal he would feel for wasting 30 years of his life