Partner Misunderstands and won't listen to reason

[Nina73]

Hello wonderful community! Long time watcher, first time poster but I really need some advice and help on a conflict I'm having with my partner (not married). Long story short - my mother recently died and while away taking care of her home/funeral arrangements I realized I did not have a will and that if something should happen to me my partner wouldn't legally receive anything. Legally everything would go to my brother, my only living relative - to make it really interesting my brother and my partner DO NOT get along at all. Since I was with my brother dealing with family matters I told him we needed to get serious and make wills to protect our assets if anything should happen to us. Since we were dealing with my mother's death I would not have the ability to deal with my personal will immediately so I told my brother that if anything should happen to me before I could make a legal will I wanted to make sure that my partner would be taken care of and receive assets. My partner became furious and said he didn't trust my brother to make sure he got anything--I explained it was only an immediate action until a will could be made -- I honestly thought he would be appreciative I was so concerned with his welfare while I was dealing with grief of my mother's passing. I had 2 choices in that moment - not say anything to my brother and hope he would do the right thing, or tell my brother my wishes and hope he would honor them if I passed suddenly (grief really makes you think about your life!) This has now become a huge conflict between my partner and me b/c he thinks I'm entrusting my brother with his future. I tell him it is only until I can make a proper will and what I did was out of love and concern. He doesn't see it this way. He looks at it like a slap in the face. Please give me some feedback - it is now causing such a rift in our relationship I don't know if we will stay together.