Questions: Relationships

I'll start by saying I realize one of the worst things one can do is to ignore someone for no reason. Well, that's exactly what happened.

I had a really great connection with a girl I used to call/text for a couple of months. We got along really great! It wasn't serious, although we often acted like it did by spending a lot of time messaging/flirting and being in constant communication.

For some reason, another girl got my attention who I went out with, which made me put girl 1 on hold. She sent me a few texts asking about me but not knowing what to say I just completely ignored her. It's now been around 3 weeks.

Now, I'm not someone who plays with people's feelings at all, much less purposely disappointing or worrying someone like that. I really did not intend on behaving that way and wish to re-initiate contact but don't know what to say.

I also don't like making excuses or even worse lying (not that I can even think of what to say if I did), but I feel telling the truth might make her misunderstand me and not want anything to do with me again, and I don't want that happening.

1. Should I tell the truth or make an excuse?

2. If I had to make an excuse, what can I possibly say?

when she said that, I was feeling really sad, and disappointed...

But she knew she was stupid, and that too naive because it was her first BF in 20 years ( she's 25 im his second, she's my first).

And she cried for 2 hours on Skype, telling me she's sorry that she's done that, she loves me and wants only me, and feel miserable to make me feel sad. And that she's soo ahsame...

And I couldnot be mad at her, and told her that even if it made me sad, I love her, and want a bright future with her.
And I trust her that she's a good girl, just did a stupid mistake.

But how to approach it now? I already care way less about it than yesterday, but should I?

How would you react?

Leave her?

Dont care and love her?

Take a break?

Other?

Feel free to explain, I really want your opinions

Vituligo is an autoimmune disease where patches of skin lose their pigment and become white. I have it on my back and on my balls, but I guess it could spread at any point. It's not that as on my back because I already have light skin. But the skin on by balls is naturally darker so it's very visible.

We haven't been intimate yet, so she hasn't seen it. She's my first relationship and I've never had to tell anyone before. Honestly, I feel like I'm deceiving her. She thinks she's with a good looking guy but I'm hiding something that could, in her eyes, deem me unattractive. I'm worried that she'll leave me because of it. The part that hurts is that it would be completely just if she did.

When do I tell her? What do I say?