Involved in a phone affair

Need advice.
My wife and I have been married for 5 years. We are both in our late 20's. Up until about a year ago our relationship was amazing. But then something changed. We are foster parents so don't always get alone time together.
Within the last year or so our sex life dried up, she became grumpy about every thing, wouldn't touch me at all and wouldn't let me touch her.
I work as a bouncer and I'm not an ugly guy, so every once in awhile girls will hit on me. I will sometimes flirt back but always let them know I am married. Liking the attention I made the decision that I wanted to have a phone affair as I call it. Met a girl online and we have been talking since, it was wonderful hearing the compliments and just the sexy talk that my wife was not giving me.
For the past 2 weeks my wife and I have started flirting again, sex has been wonderful, sending each other playful texts. I realised that I was the problem and not her.
Today phone affair girl told me that she is falling in love with me and she wants to meet. We have done video chats, I've just always made excuses why I couldn't meet up.
My question is how can I stop that without hurting her? Is that possible? I've thought about telling her the truth that I am married, blocking her number, making up excuses.
I don't want to hurt this person, I was the asshole for playing her.

Any advice would be greatly appreciated