You have a few options in this case..
A) K-1 fiance- for this visa you could not be married yet. You would have to marry once she is in the US. It takes about 6 to 9 months for the foreign person to enter the US after you apply for her. You would qualify because you are supposed to have met once in the last 2 years and have proof of it and it sounds like you two have done this. You will submit the I-129F to start the process and that will cost $535 plus a fee for the visa processing fee at the US embassy. Find it on uscis.gov/forms Again, It will take about 6-9 months for the foreigner to get the interview over in Her country. After she gets approved hopefully, she will enter the U.S., then you have to marry here within 90 days of entering and then you have to pay $1225 for the I-485
application after marriage which is for her actual green card. She will be called in for another interview here that you attend with your new spouse in about 5-6 months.
The next option:
B) If you decide to get married first in ukraine then she would qualify for the The CR-1 visa. This one takes about 9 months to 1 year before she is allowed into the US after sending the application. To begin You will submit an I-130 application. The fees are $535 for the I-130 and $325 and $120 for the visa processing fee at the US embassy/consulate
and for an Affidavit of Support fee. The good thing is that once she is approved and enters the US, she will already be a permanent resident and doesn't have to apply for the I-485 or for anything else. That means you don't pay the $1225 that I mentioned in option A. She will just receive the green card in the mail. . USCIS immigrant fee is $220
With either option, she is allowed to enter the US on her tourist visa but it will be up to the officer at the airport to allow her in or not.
I hope this helps better and hope you can kindly leave a good rating for the service and consult today. Thanks for your consideration.