can I buy a house while in the middle of a divorce in WI.

The answer is yes, subject to the title company most likely being insistent that your spouse sign a Wisconsin chapter 766 waiver of marital interest. Further, since you are not divorced, your spouse could claim a 50% interest in the house you are purchasing, so you are also well advised to consider a stipulation and order to be filed in divorce court and signed by the judge that she waives any equity interest in the new house you are purchasing.