knowing ones self worth

I have never known my Value Ive never known if I am worthy of anything. I Know I have doubted if people love me. I know that I feel like I dont deserve to be happy. I find My fiance getting sexual messeges from people he says are just friends I think thats ok because he treats me like I am always in the wrong. I find he has gay hook up apps in use with current messeges on his phone he says they are old even though the messeges are from today and yesterday so i let it go because im supposed to because he says im so lucky he is with me. I will neved do better than him. He is most likely right. Im old Im ugly Im fat I should be grateful he is with me. Why then Do I feel horrible? It doesnt matter he is having sex with other people he stays with me and I In fact should be grateful that he stays with me. this is the best I will ever do or have. Its fine. Time to bottle up these useless feelings and go to work. it doesnt matter and obviously no body cares so just keep pushing on..