Alright Salty mate?

Sounds like you do care about your current GF.
Very neasy at our age for our judgement to be clouded and for us to get misguided.

Honesty is probably the best policy. Tell her, if she thinks that your relationship is still worth pursuing, then you've obviously got something.
If she throws it away, then maybe your relationship doesn't hold much weight.

If you don't tell her though and she finds out then its game over either way.