AITA for throwing away my fiancées mothers ashes?

I, a 24 yo female, have been engaged to my husband for around a year now. We have a seemingly perfect relationship. We split bills properly, care for eachother, and have a good intimate life. This all started around a couple weeks ago, and I am still trying to process this situation and figure out if I am in the wrong or not.

A couple weeks prior to this taking place, me and my fiancée were moving my things into his apartment, since it's a more spacious place, and ironically, it's closer to my workplace than my old apartment. Now here's where the trouble begins.

I am a cleanfreak. I need everything to be clean and orderly no matter where I am. That is just how I was raised because my mother has the same tendencies. We were cleaning out his room to make space for the new bed we bought, along with my other necessities I brought along with me. As we were moving out his old twin size bed, I found a tupperware container underneath the bed. It wasn't marked, nor did he tell me what it was. I assumed it was old food left under his bed since the container was foggy, so I marched to the kitchen to throw it out. Later that night, he began frantically looking for something. When I asked what he was looking for, he said he was looking for his moms ashes. I offered to help because that's what any normal person would do, and that's when the search began. I asked him what the urn looked like that he kept her in, and what he said next made my stomach drop. He said she was in a tupperware container due to the fact that he still couldn't come to terms with her passing (this was two years ago that she passed).

I turned pale, and when I told him I threw them away, he lost his mind. The story could've ended there having found them, but the only problem was, the garbage truck had already came to pick up the garbage we threw away.

Long story short, after a big argument, I am staying at my moms and my fiancée has ceased all contact with me for the time being. I feel horrinle, but also, who keeps their moms ashes in a tupperware container?! Am I The Asshole?