Why would Christ teach us to be self sacrificial?

I just don't understand. Today my beloved cat died at the hands of selfish neighbors who would not contain their dog. Before this i'd ask the neighbors kindly to keep their dog off my property, but she essentially responded that she had her own problems she was dealing with, so she couldn't be bothered to try any harder than she already was. ( I saw She had police at her house the day before and her and some of her household members had been fighting) So I empathized. Despite the fact that I was so angry at the fact that because she was suffering, she didn't care that she was causing suffering onto others (at the time her dog would go in our trash and leave it all in the yard for us to clean up) I still empathized, I didn't try to impose my way. I just decided that id turn the other cheek, like Christ taught us. But if I had been more demanding, more SELFISH I would have pushed for a resolution instead of allowing this woman and her issues to override mine.

This post isn't about my cat really, it's about what losing her made me realize. Why would Christ say turn the other cheek, why would we be instructed to put others before ourselves? And to look out for the interests of those around us before our own interest. You see, I try my best to do that and trust that even tho I don't receive the same back from others- my reward will be in heaven.

But today I realized that by doing this I could lose the ones I love. Not just my cat- I just had a baby boy, he's two months. I'm married to a man- probably the first person who's showed me genuine unconditional love. All I want to do is keep these two good things in my life. All I want to do is protect the little bit of good I have. And I fear that if I follow these instructions that Christ and his disciples gave then one day I might lose them.

I'm so upset. Why would God give us these instructions? He knows how brutal this world is. He knows selfless people are the ones taken advantage of. I want to please The Most High so bad but I'm having an impossible time reconciling this issue. Can anyone help me? My faith is on the line.