@katied29,
Yes, if that was what your brother did with you, it was definitely inappropriate physical contact, and a form of sexual abuse of an 8 year old.
I definitely think you should see a therapist and discuss how these memories are continuing to affect you. It actually doesn't matter whether your memory is fully accurate regarding the actual past events. What's important, in terms of your emotional well being, is that your current sexual intimacies seem to arouse associations of some past trauma or something unpleasant for you. That's something you have to explore with a therapist, and not with your brother.
I don't think you should ask your brother to confirm your memories, or even broach the subject, at all, with him now. Regardless of what your brother remembers, or cares to admit, you still are having a
current problem that you need to better understand, so it won't continue to affect you in a negative way, including a feeling of shame, or a sense of discomfort with sexual situations now. And that's what therapy will help you with.
You are getting inaccurate information from other posters. If you speak to a therapist, the information will be kept confidential, between you and the therapist--
there is no "mandatory reporting"-- to anyone-- of this sort of thing, so do not worry about that.
Mandatory reporting is only done when a minor is being harmed in a way that requires some immediate investigation and intervention by Child Protective Services in order to protect the welfare of the child involved--and, in such cases, the reporting is done to CPS, and not the police.
You are no longer 8 years old, you don't need CPS to investigate whether you are in an unsafe or abusive living situation with your brother now that requires their intervention. That's all in the past. So, let me reassure you again, whatever you speak with the therapist about will remain confidential and private, it will not be reported to anyone, your brother will not become involved or affected by anything you tell the therapist. It will only be between you and the therapist.
And, please do seek the help of a therapist, katied29, you are being troubled and affected
by something, whether it's that "game" you remember engaging in with your brother, or possibly something else in addition. And you have to get a better understanding of it in order to move beyond it and put it to rest. Life is much easier and happier without that sort of emotional baggage. A therapist will help you unpack it.
Good luck.