Sex and love

My boyfriend told me he wants to have sex with other people and wants me to be okay with it. He said he is going to do it regardless of how I feel. He loves me and doesnt want to lie to me so he's being open about it. He also said I can have sex with other people too but I don't want to. I love him and I am not okay with it. We have been together for 4 years and he has always been loyal but now decides he wants this type of relationship. What should I do? I love him too much to walk away