Husband Sucks in Bed Now

He used to be so good in bed it was amazing. He was romantic and took time to satisfy me. We had our son which he said made him even more attracted to me but as time went on we've had sex less and less and he started to be terrible at it. I get it that we've had a rough time being first time parents at first but damn. Sex happens once a month and it may not even be good 😣 He refuses to go to a sex therapist (or any one for that matter), he's against toys, and he hates any form of birth control (but I take it because you not gone catch me having another kid with him if this is how it's going to be). At this point I'm sexually frustrated, I feel rejected all the time as he says he's tired a lot (which I get because he works hard) or he's not in the mood, and I'm unhappy. I masturbate behind his back almost everyday because he's against that too. I've tried watching porn with him and initiating sex. At this point I'm over it and fantasize about getting fucked by other guys (even though I'd never act on it). I want to work it out because I believe marriages can be great if you work out issues instead of jumping to divorce and deep down I still love him. We are a young couple both under 24. I'm not sure what to do at this point but if you have any suggestions please share.