I think my mom is having an affair

I think my mom is having an affair.should I tell my dad?

No, not without any type of proof.
If you have proof though, I would go to your mom first, and tell her that you know what's going on, and your dad has the right to know.
Tell her if he doesn't tell him then you will.
If you have no proof though, and this is just an asumption, you could cause a lot of drama between them and also between your parents and you. You can't just throw around false aqusations like that.

No, you should leave it up to your mother to tell him.

If you tell him, it's bound to make the experience even more humiliating for him.

Tell your mom that you know, and if she doesn't come clean (or end the affair), then you will tell your dad (bluff).

first ask yourself how your mom treats him, if she treats him poorly let your dad have fun...but if she treats him right then keep an eye on him and when you have hard evidence tell your mom

No. You should talk to your mom instead.

it would be wise to but then again my mom was and I told my dad and he went back and told her and my life hasnt been easy for the next few months after that and only reason it got better was because I got removed from my moms home just make sure if you tell him that you make sure he is going to be there by your side

Must have proof first - confront her with it - if it doesn't stop, tell Dad - if he's being cheated on, he should know, it's wrong.

I'd say its none of your business unless it's having a negative impact on you, in which case, have a chat with your mom about your concerns. I don't think you should be at all confrontational or judgemental.

 
You can confront your mom but you should NOT tell your dad. If you were to tell your dad and because of that they break up, it would always be YOU who caused their break up.

It is quite possible that he already knows. You would just be humiliating him by letting him know that you know.

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the first think you should do is to ask your mom to be honest to you and ask her if she is having an affair if she says yes try to keep it a secret if she does not answer then you must try to find out yourself but if your dadis violent type DO NOT TELL HIM!!! But if he really loves your mom he will ask her to stop liyng and to tell the truth!!!

I think you should wait and see if there are any evidence that she is doing this... because I was in the same position as you a while ago when I thought that my dad was having an affair... but I didnt say anything to my mum about it for ages .. I kept it to myself which is hard to do and not good for you. Look for little signs like if she does not let anyone tough her phone, carries it around with her all the time or if she always deletes all her messages or if she makes secret phonecalls away from everyone. If after a whilee you still feel the same then talk to your mum about it and ask her to be honest with you.If it turns out she isint then you can leave it there and maybe appalagise to her, if she tells you that she is then its something that yous cant keep from your dad as it is not fair on him. Ask your mum what she really wants and tell her to talk to him and to be honest with him... its better that she tells him herself rather than him finding out later on in the future from someone else. wish you luck on whatever you decide to do and hope everything turns out ok!

I have alredy gone through similar situations. My father has been working In Middle East country for few years. He visits after one year. I had a doubt that my mom has affair with dad's best friend so I kept watch. I watched all incoming outgoing calls, recorded messages. And when I checked her mobile phone messages while she was taking bath, I came across with one SMS on my mom's mobile that said, I will take sicki tomorrow as you have RDO. Will come to your place around 10 AM. It was clear to me that they are definitely having affairs. So, I deliberately returned my home around 10:30 AM found my dad's friend's car parked at my house. My mom's bedroom windows were closed but there was slight gap in glass fittings. I saw inside her bed room found my my mom fully naked with this man. I dont know what made me stand there but I ended up watching my dad's best friend shagging my mom.
I had mixed feeling. I was terribly shocked. Although I love my dad but I am more attached to my mom .I felt that if I tell my dad than it will ruin my moms life. So, I just kept quite. I felt that probably it is unreasonable to expect my mom to sexually starve for one year secondly I felt that it is none of my business any way. So,Mom still continues to have good time with this guy as she is not aware about my knowledge but what surprised me is the fact that this guy after bonking my mom calls my dad from my home my mom his friend talk to him for at least half an hour. I am not sure whether there is any unspoken silent understanding between my dad, mom his friend or he is naive? I feel odd that my dad never seems to have any issue with the fact that his friends spends time with my mom when no one at home. I get surprised when my dad thanks his friend for helping my mom. I also believe that every affairs dies after some time. Since my Dad mom love each other, I feel that mom's affairs is not really emotional will end at some point of time