u/Dazzling-Carob-4891

I 22F have found myself in a very confusing relationship dynamic. I have been seeing someone in his late 20s. I met him at a place I worked at. He is pretty cool I guess but he has a girlfriend. He says he wants me to be his girlfriend as well. He wants two woman at the same time. Here's the thing, he is very open about flaunting me around publicly and treats me like his girlfriend. HE HAS A GIRLFRIEND ALREADY. He is very territorial but he expects me to be loyal to him regardless. He has no problem giving me his emotions, time, money and anything I ask. But this situation is destroying me not only mentally but physically. I have been experiencing unhealthy ph imbalances and extreme anxiety/low self-esteem.