Fantasy with my mother-in-law... what would they do?

Hi, my name is Federico, I'm 26 years old and in a relationship. Let me describe myself: I'm 183cm tall and weigh 70kg. Slender build, but not too bad, since I've been doing sports since I was 9.

Well, the story is about the fantasy I have with my partner's mother. She's a woman around 50 years old, has a body that looks great for her age, although she says she's overweight. Let's say she has quite admirable breasts, and a waistline that's a bit wide due to her precious booty. This drives me crazy and has been keeping me trapped.

I didn't pay attention to her figure until I had a child (9 months ago), and maybe it's because of the lack of sex (parents understand) or that she really gets my head spinning.

She comes to my house every week since we live close by, and I always try to find a way to touch her, support her, or something. I look at her with an appetite to eat her whole and think she knows or notices it like any woman does.

Several times I've gotten close and could feel her breasts rubbing against me, and once while changing my baby's diaper, she touched my penis several times. I never knew if it was intentional or not, but since then, I haven't stopped thinking about being with her.

Several times she came when I woke up, and I always get out of bed wearing athletic shorts that are lower than normal, trying to make my penis stand out as much as possible so maybe she'll say something someday. My penis isn't small or huge, but it's quite wider than average (I used to do sports in the locker rooms with all men naked, that's why I'm saying this).

Well, honestly, I don't know what to do about this situation since if it's just my imagination, it could become a real family disaster. And I don't think I want that, so I'll have to... Living with this fantasy for life. What would you do in my place? (This is my first story, and I'm telling you something that drives me crazy, sorry if it's not to your liking) A greeting.