<human>: Can you provide a brief overview of the text?

Hey guys, 
I will keep it short:

when I first dated her, I told her that I had a girlfriend 4 years before her (when I was 20), and that she was the one I had my first time having sex with.
The thing is: I lied. I was too embarressed to tell her, after our fifth date, when sex was imminent, that I was a virgin. I crafted a fake story, to make it clear, that I am very inexperienced. 
In fact, she even is my first girlfriend. So I told her I have been in one short relationship (6 months).

It was out of embarressement, and I didn't want to ruin the moment. She shouldn't feel pressured, to make it something extra special (even though it was for me). At that time, I didn't know if she was looking for something serious or not, and I made that kind of dumb mistake.

Of course, the topic came up a few times later (questions of my former girlfriend ect.; I told stuff like "my parents didn't know about it; my friends are spread across the country, so we rarely see each other ....), and my lie seems to be very bullet proof. She doesn't seem to notice one bit.

But I don't want to lie to her anymore. I really love her, and lying is a no-go. On the other hand: that is the only lie I ever made towards her. It is kind of a big one, but also a small one. It doesn't hurt anyone. Just me atm. 

So: how would you react if your SO tells you, that your bf was a virgin before? 
Would you be angry?

And just hypothetically:if you can take that (insignificant?) lie to your grave, without her noticing, and both of you are very happy: would you tell about it?

Thanks btw, for the very helpfull community!
<bot>: Told my SO (when we started dating) that I had a previous relationship, even though she is my first everything. Would you tell her afterwards?