I Caught My Uncles Wife Pant Down With Their Gate Man

My purpose of writing is to get people's opinion on what to do.
I arrived Lagos about three months ago to stay with my uncle and his wife, who's an Ibo woman. By the way my uncle is from Edo State and their marriage is about four years without kids. In the last week of August my bros travelled to the North on official business and something happened in his bedroom.

I came back that day because I could not meet up a job appointment in Igando area due to heavy traffic. I
was reluctant to return home since I had just left but I couldn't think of a better place to go so I headed home. On getting to our compound, I didn't find the gate man at his post and I was even angry because of the security risk of him leaving the gate open like that.

But something got me worried when I saw the gate man's sandals right inside our sitting room. I just told myself that something is going on between my uncle's wife and this dirty boy. I was right, when I moved close to the window of my uncle's bedroom I started hearing screams of sexual pleasure from his wife. I tried to peep into the room but it was difficult because of the protector.

So, I summoned courage and walk to the door as if I wanted to tell my uncle's wife that I was back. I opened the door and caught the adulterous woman red-handed under the dirty gate man (boy). Sadly, the gate man was already ejaculating so he couldn't get up immediately, it took him few seconds to jump off and grab his clothes.

I simply walked away and returned to the sitting room, pretending to be watching a programme on the TV. Few minutes later my uncle's wife joined me and started begging that it would not happen again. I didn't say a word but when she kept pressing I said ok I've heard. Later she brought food for me but I refused it and since then she has been putting pressure on me.

The unfortunate thing is now she even wants me to sleep with her as an assurance that I wont tell my uncle, always coming to my room half naked. Because of this I've not eating in the house in the last one week, I'm almost going broke already.

My uncle may be back next week. I will like people with more experience to tell me what to do when he comes back. Should I tell my uncle the kind of wife he married or quietly move out?