[I]f you're Jewish, do you go to heaven when you die?

Sure, if you accept the substitutionary atonement of ישוע (Jesus) HaMashiach! Jews are indeed the Chosen People, but this is not a statement of salvation. The Jews are God's adopted, earthly family, if you will. Disciples of ישוע (Jesus) are Jews, too, even if they are merely grafted into the family.

It's a popular heresy that Jews were once saved by the Chosen status and that they lost their salvation when Christians took their place. There's more wrong with this than I know where to start. The status of Chosen is one of a special relationship in the here and now, not a statement of eternal salvation. There has always been only one way to salvation: ישוע (Jesus). Always. Those who came before knowing His name could be counted as faithful because they trusted in the Lord's salvation apart from anything they could earn. They put their trust in the Lord, and this was exhibited by their obedience. Likewise, our faith in the Lord today is exhibited by our obedience. (This is a major point of James.) Nothing has changed.

In fact, there are very few new doctrines introduced in the B'rit Hadashah (New Testament) that weren't already well established in the Law, Prophets, and Writings. (The only new doctrines in the N.T. are actually very minor. For example, the fact that the Kingdom will be specifically 1000 years long.) Salvation by faith alone is exhibited throughout the book of Isaiah and is nothing new to the N.T.

The Law was never a means to eternal salvation. Obedience to the Law may considered a symptom of salvation, but as any parent knows, even obedience may be born of a loving relationship or of empty rote. The former indicates a saving faith while the latter does not.

Jewish customs today, as they are popularly known, are not Biblical in origin at all. Obedience to the Law today among the Orthodox, for example, is actually Talmudic and not from the Torah. The former is what ישוע (Jesus) called the oral tradition (later written down, of course, in the Talmud). Today's Jews, as a lot, have little to no clue what the Torah says--of course, neither do most Gentiles! As such, they have perverted Judaism into something that often denies a relationship with the Lord. Without a relationship, there can be no saving faith.

Having said this, salvation is available to the Jews just as it always has been. The way to salvation is the same for Jew and Gentile alike (although the latter is adopted as the former when they are saved). The way to damnation is also the same for all: denial of ישוע (Jesus).

Interestingly, according to Zola Levitt (a Messianic Jew now with the Lord), the percentage of Jews who believe in ישוע (Jesus) is actually about the same as the percentage of Gentiles who believe in ישוע (Jesus) ("Gentile" referring to their pre-salvation, unadopted status, if you will). In other words, you can make no more generalizations about Jews' salvation than you can about Gentiles'. Being Jewish is no more damning or saving than being Gentile, statistically speaking. In the end, it always boils down to a choice to accept ישוע (Jesus)'s atoning sacrifice or not.

As for Christians "converting" to Judaism... Let's understand this: such Judaism as requires formal conversion is, in fact, not the Judaism established at Sinai, but a perversion begun largely in Babylonian captivity and thereafter codified in the Talmud. Secondly, Biblical Judaism is not mutually exclusive with Christianity. In fact, in their truest, most Biblical forms, these two--Judaism and Christianity--are one and the same. (I should note that modern Christianity is just as perverted from Biblical definition as modern Judaism, albeit largely out of antisemitism.)

In my experience, this kind of "conversion" is actually an explicit rejection of ישוע (Jesus) in favor of Talmudic "Judaism". In most cases I've known, such converts had to explicitly deny ישוע (Jesus) as part of the process. (I know of one exception I think was protected by God Himself.) If this is generally true, then this conversion to Talmudic Judaism is sadly damning. Of course, church doctrine is one thing, while personal choice is another. Such a personal choice to accept the free gift of salvation through ישוע (Jesus) can be made at any time, leaving us room for hope for our loved ones who previously rejected ישוע (Jesus).

If you would like to hear first-hand how Jews can be saved, drop by our synagogue at 11AM some Saturday. You'll hear exactly what Wayne has said, which is that Jews are saved through faith in ישוע (Jesus), who was, is, and will be the Jewish Messiah. (Oh yeah, He saves Gentiles, too.) All are welcome at Beth Adonai, and in fact the congregation is overwhelmingly Gentile. We attend there in part because it is comforting to hear Christ Jesus preached as what He is, the Jewish Messiah.

I would not discount the grace of God or try to guess her spiritual condition over those last days or hours based on what you knew of her previously.

Samuel Johnson said something like, "When a man knows he is to be hanged in a fortnight, it concentrates the mind wonderfully." Her perspective may have changed substantially when she discovered she was facing eternity...and God is OK with that.

Was this your aunt that lived near Silver City? If so, I'm sorry for your loss. Grace to you and your family.