Just to shut him up !!

So I'm currently 14 weeks pregnant with baby #4 I have a 7,5 ,1 year old already , youngest is to now partner . Anyway , we have gone sometimes 2 months without sex , but lately his wanting it atleast a few times a week. That's all well and good , but he doesn't help with our daughter at all his only ever changed 3 nappies . I also work full time and study online full time , so all combined I'm exhausted to say the least .. Last night he went o gym and then didn't come back to my place all because I didn't want sex !! So tonight I just gave in and have it to him to shut his bloody complaining up . Now I'm frustrated and feeling used for his needs only .. This so more of a vent ! But please tell