In which state do you reside?
If it is a community property state (Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, Wisconsin), you can use Self-Employed and each file on a separate Schedule C (i.e., you will split the income and expenses according to your interests).
If you are not in a community property state, you will most likely need to file a Form 1065 and issue a K-1 to each of you.
Concerning the latter, you are probably going to need help and should seek local assistance from someone knowledgeable.
