Also his sexual life with my mom before she passed. Dad is 87 and has been diagnosed with Alzheimer's and has started discussing his sexual conduct in the past and it is starting to become a worry that he will start discussing this with others besides myself or my sister. How do I help redirect him when he starts these conversations?
It can be difficult but you could simply not react to the stories but move on to another subject. If it is a story about your mom (his wife) you might respond with something like "you really loved mom, didn't you" or "mom was great and we all miss her" or "tell me about how you and mom met". It can seem awkward but worry less about what others will think of him or you if he tells those stories to someone outside of the family. He has dementia and will engage in a lot of behaviors which will be difficult to explain - it is simply part of the disease and part of the caregiving process.