Hey! I can only imagine how difficult it must be for you.
Have you tried confronting your partner?
I can understand your pain , you are not alone , I'm just 19 idk what to do but I can't just ignore this because of that , I pray for you. Let everything happens good for you
U need to confront them about this and leave them. There should be no reason to stay in that relationship if you are the only one loving. You deserve so much love and happiness. So u need to pick ur health over a shameless person
Confront and if you don't see remorse or good promises of proving themselves then leave