If you say that, it means you got married 10 years ago and you are still married. Of course, it is possible that this current marriage is not your first one, and that you got divorced some time more than ten years ago. But based on that sentence, you are still married to the person you married ten years ago.

I was married for 10 years. Then I got divorced. The way you phrase it gives the sense that you are still married.

If you say "I've been married for 10 years," I assume that you are still married. I am not certain if the sentence has an ambiguity. If you want to convey the idea that you are divorced now, one simple, short, unambiguous phrasing is "I was once married for almost ten years." "Was once" indicates that you are not married now. If you want to convey the idea that you are still married, you could say "My wife and I have been married for ten years." By including the word "wife," rather than "ex-wife," you convey the idea that you are married now, to the person you have been married to for ten years."

to throw my idea in on top of the others: "i HAD been married for ten years, then I got divorced. I have been happily married to my second wife for 10 years"

"I've been married for almost 10 years" does not mean that you are still married. That is the most likely interpretation, but how the sentence will be interpreted depends on why you say it, to whom you say it, and how much they know about you. Here is an example to clarify this. Suppose that you are preparing a recipe that requires that some beans be soaked for one hour before using them. Suppose you soak them for an hour and forty-five minutes and then put them aside for an hour. You can then say "these beans have been soaked for almost two hours" even though they are not still soaking.