Can separated wife get child support from (me) the custodial parent?

Colorado - My wife and I never got a divorce and have had a verbal agreement on who get's the kids for the past 5 years. We agreed on 50/50 (verbally), but I actually have had them more nights per year. Anyways, I am now happily living with my girlfriend and have just had a daughter with her. My wife has lived with her boyfriend for longer than I have lived with my girlfriend now and I have not asked for child support from them. My wife is angry that I have a daughter and doesn't like my girlfriend. And now she says she wants child support.

I can show that I am the custodial parent (they live with us more) so can she request child support when I have the kids more, and have a new daughter to take care of as well?

You would have to get divorced before any order of child support would be justified.

Thanks for the reply. Could she file for personal support of some kind (alimony or?...) while we are still married? For some reason she thinks she can get monetary support from me (because we are still married) but she's been living with her boyfriend for years now, and he has been supporting her.

No. Only a divorce will accomplish that. She cannot get alimony if she's legally married to you.