Had sex with a girl while my ex was sick in the toilet [MFF]

My ex and I used to try to have a good time and find people to have threesomes with. This one time we finally found a girl join from tinder and we had a lot to drink and started having fun. My gf had the spins and was puking in the toilet. I checked in on her to make sure she was OK and she told me to go away. The tinder girl was just laying there and asked if I still wanted to have sex and I said of course. I felt bad but I kind of knew my ex and I’s relationship was coming towards an end anyways. [MFF]