It is permissible for a Muslim man to marry a Christian woman.
حل لهم والمحصنات من المؤمنات والمحصنات من الذين أوتوا الكتاب من قبلكم
[lawful in marriage are] chaste women from among the believers and chaste women from among those who were given the Scripture before you
— Quran 5:5
By extension it is permissible for a convert to remain married to his Christian wife.
She and any non-Muslims in your family can continue to eat according to their religion. There might be certain exceptions e.g. if you have infant children who get suckled, in which case you should ask her to not consume haram food in that period.
Note that according to Islamic law any children who are not adults (below puberty) are going to be Muslims following your conversion. How to resolve this with your wife is something you are going to have to figure out.