Polygamy relationship with my boyfriends ex wife

Sara

So my boyfriend and I have been together going on 8 months now. Every day he talks about wanting to involve another women in our relationship. He and I both agreed that we could possibly ask his ex wife if she’s interested? Mind you, me and my boyfriend are 19 years apart and he has 2 kids with his ex so he’s wanting to keep positive people around his kids and his ex wife isn’t the most positive but because she’s getting her life on track, he wants to make sure she is still able to be in their kids life. Am I crazy for agreeing with him?