I would tell the truth. When I met my now ex, she asked me the same thing. I was sleeping with 3 girls at the time, multiple times a week.
When I took her out, I did it under the pretense that I was going to show her a good time and that was it. She fell super hard for me and eventually asked me to stop sleeping with other people. I told her I would sleep on it despite the fact that I knew I wanted her the most. I also told her, after agreeing to be monogamous, that I would need a couple of weeks to tie up loose ends. This not only raised her level of interest but made her feel like she had to work for it. She was an HB9-10 depending on your preferences but objectively was extremely attractive. She also made me get tested before she would sleep with me, which I have a lot of respect for—no girls do that these days. She had only slept with a few people.
At the time, I was also unsure of what I wanted but my plates we’re replaceable and physically, she was not. Because she was so hot, I was less interested in banging other girls.
Just something to consider, but if her interest level is super high, this will, at the minimum, test that. At the worst, you’re just being honest. I find that being unapologetically honest goes a long way with a quality women and the only times I have gotten into a mess is when I have lied.
I am also against cheating fwiw. If you’re not going to be faithful, don’t commit. It’s not that hard. Being a man of your word is in essence very much a part of being a DJ. Lying, cheating, and sneaking around is not. You will eventually get caught, it’s bad for business and reflects poorly on your character.