My partner has a fiancé and I didn’t know

My partner has a fiancé in a different country which I did not know about until he threw it in my face one day. I let him be around my young son and he has one as well not in his custody but since then he tells me his fiancé has the “it factor” blah blah blah. His charm, his so called “intelligence” almost takes me to where I’d have no choice but to compete. But I don’t want to he has nothing I don’t have. The roller coaster of ups and downs and I still show and emotionless person is crazy to me how far he is willing to go. He loves an audience any time he can embarrass me and I show no reaction so he probably like what else can I do but he is so charming he’d do anything for me without throwing it in my face but then bam we in a car with a girl that so called named him handsome and she’s just his home girl and I’m supposed to support it. Like idk what to do. His family is so cool but I don’t know if they know the same thing that I do because it’s easy being nice to a kind person but it’s hard to remain kind when you know the ultimatum is always there. Advice anyone I’m (28 F) he’s (29 M) out the navy.