'Cause then.../If not...

Hello.

1

So maybe you're not that intimidated by it anymore? 'Cause then you might as well join me when I'm going tomorrow. I promise you won't be the only man there.

2

So maybe you're not that intimidated by it anymore? If not, you might as well join me when I'm going tomorrow. I promise you won't be the only man there.

Question:

Are 'Cause then and If not both natural here?

And is the rest of it correct, too?

Thanks a lot.