My mother-in-law and me get along pretty good but she began to get a little more relaxed with one thing. The one thing was anytime that I was going to be changing, showering or using the bathroom she would not leave as quickly as she used to. It now began to appear that she would stick around hoping that I would possibly tell her she didn't have to leave. Well one day I was at her place and her neighbor has a swimming pool which she invited us over to use. I didn't have a swimsuit but my mother-in-law said she had a few and that one should fit me. She said I could change in her room and to start undressing as she went into her closet to get the swimsuits. She had seen me in my underwear a few times before so I did begin to undress. She was quick to find 3 swimsuits, handed them to me and sat down on the bed. I had only taken my shirt and shoes off by this point. I took my socks off next wondering when she was going to leave. I began to take my pants off next and was now in just my underwear. She remained sitting on her bed and wasn't moving. After about 10 seconds of me just standing there and her just sitting there watching me she asked me what I was waiting for. I told her my underwear was coming off next. She said she knew and to take them off. I mentioned that I would be naked. She got up but instead of leaving the room she came over and removed my underwear for me. It was unexpected so I just stood there naked. She went back to sitting on the bed and told me start trying on the swimsuits. I wasn't so concerned about her seeing me naked as I was with what my wife would think of her seeing me naked and I mentioned this to her. She told me we didn't need to tell her and I began to try on the swimsuits. As I tried on the swimsuits she told me I shouldn't be shy with her seeing me and went on to say with the kids she had, the kids she had babysat, her dead husband and her ex-boyfriend's she had see quite a few penis's in her lifetime. She then added that my penis what the first one that she had seen in about 20 years that was not on a male that was younger than 12 years old. That was a little awkward but it was arousing to think that she is the one who put me in this state. When I had decided on the swimsuit I was going to wear she said she was going to get dressed now. I think she was waiting for me to leave but I did as she did and just stayed. She paused briefly but began to start undressing. She took off all her clothes and I got my first look at her. I think she was enjoying the attention because she was in no hurry to get her suit on once she was naked. She even came over at one point to ask if she should give her bush a quick trim even though she didn't have much hair there. When she did this she had used her hands to move the little hair she had aside and pulled her lips open in the process. I saw her clit and she noticed a smile on my face. She asked why and I told her what I had just seen. She then pulled her lips open again like she had done earlier, looked down and noticed that her clit was visible to me. She made the comment she wasn't meaning to do that but said what was done has been done. She put her swimsuit on and we went next door to the pool. We spent a few hours at the pool but the neighbor had to leave after an hour but said we could stay as long as we wanted so we did. When we decided to leave my mother-in-law suggested we rinse off the chlorine the pool contained by using a shower her neighbor had setup. We shared the shower together and removed our swimsuits while in there. There was some soap in there so we quickly lathered up and we did help each other a little during this part. She then suggested we lather up each other and we did. We probably shouldn't have because our hands eneded up touching each other in parts where a mother-in-law and son-in-law should never touch each other. This did get very heated but we did manage to control ourselves by not going all the way. We went back to her house naked just carrying our swimsuits. We did have a talk afterwards about what happened and decided we would keep this just between us. When I was getting dressed to leave she told me if I ever wanted to have a little fun with no strings attached she was up to it and promised she wouldn't tell anyone and that I wouldn't need to worry about getting her pregnant like I would with younger women because she was past the child bearing years.