Relationship issues

Me and my partner have been together 5 years , we met when I was 18 we spent every single day together and he ended up moving in with me and my family within 6 months , naturally I stoped going out with friends as much but still had some what of a social life , anyways 5 years on we have a 8 month old and our own house together , lately we haven’t been getting along , he can be quite mean to me verbally sometimes such as saying he thinks he hates me and doesn’t know if he wants to be with me etc, we never used to argue and now it happens a lot , he can be nice to me one minute and the turn the next , obviously since having our daughter our relationship has changed , we don’t have sex much anymore and this is a big problem for him and is what start most of the arguments , me personally am not too bothered which to him is the issue , but when you are a stay at home breastfeeding mum the last thing you want at the end of a busy day when you are tiered is to have sex , today we had a big argument where he pretty much said he doesn’t like who I have become and I am not fun anymore , he doesn’t understand that this is just a phase and is not permanent but he won’t listen , even after all the arguments and the mean things he says to me I would never want to be without him , is it because I love him that much or because it’s the easy option honestly I’m not sure , he also said that he thinks he is a sociopath and doesn’t feel guilt or multiple other traits I’m not sure he has the tendency to be over dramatic when he Is in a mood , I’m not looking for advice per say I just needed to write this out as I have nobody to talk to , I don’t like talking to my friends and family about our problems because I don’t want them to think he is a bad person or anything it would be nice to talk to others that are maybe in the same position or if anyone has advice on how we could improve our relationship, I don’t want people to just tell me to leave him etc