My fiancé wants to have a three way with my best friend

Katelyn • Pain is only temporary ✝

So my fiancé has been insisting on having a three way, and tonight my girl best friend came over to my house to hang out and make sure I was okay. (I have been in and out of the hospital for the past two months) So tonight my fiancé started pushing really hard to have a three way with her and I. When I told him I was in to much pain to go through with anything along with was not comfortable with the idea he got pissed at me pushed me away wouldn't talk to me and now is icing me out. Him and I have been together almost 3 years. Our wedding is in a year, and I may be pregnant with his kid. What do I do? And how do I get him to stop with this whole three way thing?