Threesome

So my husband and I hardly ever have sex anymore, he never holds my hand, we hardly ever kiss anymore or really even hug. I feel he's not attracted to me because I've gained a lot of weight due to having a baby 9 months ago and being 7 months pregnant now. Anyways. Last night we FINALLY had sex, for like the first time in a month, only because he asked me to give him a bj and then told me he wasn't going to have sex with me and I told him that wasn't an option so I got on. So while we were having sex he asked if I would have a threesome with him and one of my friends. I told him I don't have any friends and I don't want to anyways and he kept on and kept on and I finally told him if he wants a threesome that bad he can have it with me and another guy and he flipped and said that's different and I said it wasn't any different and its an insult to me to ask me to bring someone else into the bedroom when I feel he's already not attracted to me. Do you think he wants to have sex with me and another girl because he's not attracted to me and he's bored with me or what? He's never brought anything like this up and we've always had the agreement that nobody else would come into our relationship because we don't share. Idk. I'm just so confused. And yes I know most men have this fantasy, but my husband has never been that kind of guy. At least I thought. 😕