Is it widow or widower in a same-sex marriage?

There are a lot of widow questions here on SE.

My same-sex partner has passed away, and today I referred to myself as a widower. But it appears in the Collins English Dictionary that a widower is a man whose wife has died and who has not remarried. It also has a very heavy connotation that I was married to a woman.

Is it exclusively any man who loses a partner is a widower, and any woman (even should she be in a same-sex marriage) who loses a spouse is a widow? Is there another term more appropriate for me to use?

@Davo6 is right above that these terms are being expanded from their original context and time will tell how they end up being applied.

At the moment, widower is the term for a bereaved male spouse and widow his female equivalent. The male term is much less common, but male survivors of mixed-sex marriages are much less common. If you don't like the noun, there's always the plain adjective bereaved.

You're right about the connotations... but marriage itself has those connotations to some and, even where it doesn't any longer, it did until recently. You are part of the first generation to deal with this part of the human experience in the open. You can choose any term you like and the rest of us will just share our condolences on your loss.