Visitor Visa - B2

so here i have a question and i want to thank everyone in advance for the help i could or will get,

situation: im a us citizen since birth. i met by boyfriend over 1 year and half ago. he proposed and everyone was to excited.... but he came here on a visitors visa (b2) and has overstayed that visa, by a lot. sadly my soon to be father in law is sick in mexico pretty much not going to make it. is there anyway of us getting married and going and applying for a fiances visa. or what am i to do..

we were planning a huge wedding but i want my father in law there and he wont make it in to the states if he even tried.. i mean i dont know what else to do; i know he has broke the law and i understand theres consequences but is there anything i can do to have him come home with me for our wedding here?