yes we're planning on meeting someday but for now we can't really do much)

Unfortunately, unless you actually meet up several times for extensive amounts of time, there's no way to figure out if you're actually compatible. Dating online and in real life is NOT the same.

And yeah, you sound a bit codependent.... That "I won't ever leave you" is simply not realistic. Most relationships break apart due to factors outside your control like growing apart, or falling out of love.

What should i do? how should i tell her he's not just a friend but is actually my BF and we're in a LDR?

Again, there's nothing you can do. Ld comes with tons of problems.... you can't meet each other, the honeymoon period stays alive longer, you don't really see red flags etc. etc.