Your voice sounds fine.
Regarding the distortion you probably are overdriving the preamp on the soundcard. There's not much you're going to be able to do about that. The Beta (57 or 58?) may help some ... but what you need is a decent preamp.
Of course, you're not going to want to run out and spend money on something that you're not likely to use very often ... or are you?
There are a ton of USB mic pres that are fairly inexpensive. Or you could go with something like this:
SameDayMusic.com: BLUE Snowflake USB Microphone
(you'd probably need to find a dealer in Portugal).
Having said all that, ultimately it's up to you and whatever you give us we will work with.
If you record your part at 24-bit (if that's an option) as softly as possible to avoid distortion but loud enough that we can work with it I think it will be fine.
I'd recommend everyone record at 24-bit if possible. If you can't record at 24-bit that's fine but if you can that's even finer.