My memories of it are extremely vague. I was about 10 years old when I played it. I managed to complete the game once before the disc cracked and became unplayable :(

It was a space combat game for PC, pretty graphics IIRC. As long as I can remember, it was pretty hard -- though I hardly recall any easy game of old. Story-wise, I remember nothing. Campaign-wise, I only remember the last mission, which was divided in 2 parts. The first part was to get past a big fleet of enemies in space and catch a massive Destroyer which was opening a wormhole before it could complete it's jump. You go through that wormhole and that part ends. The second part was inside the wormhole, you spawn behind the aforementioned Destroyer who is now shooting at you, and you have to destroy it's core to defeat it. After you win, it all ends in a cinematic of the wormhole opening near Earth, the Destroyer coming out of it in pieces. You die thanks to the explosion you caused.
Gameplay-wise, it was all in first person. You could shoot to different parts of big ships for different purposes. You could control the speed of your own ship. I think you had missiles, but they were very limited per mission, without any chance of getting more.

It's very similar, both in looks and gameplay, but that's not the one.
Oh, I just checked it's predecessor's ending. It's Freespace 1. You were close enough! Thank you for the hint :)