husband won't have sex with me

Ok ladies, been married for 3 years now. Had a great sexy life in the beginning then after I got pregnant with our first child sex life plummeted. We fight a lot and we he had issues with watching porn and sending dick pictures to random women online. Which almost ended up in divorce. Now I juts gave birth to my 3rd baby, he's now 2 mo. And we didn't have sex before I gave birth and after, probably 4-5 months now. Before that we'd have sex once every now and then if I get lucky (1 a month or twice). I'm so tired not feeling wanted, and always being rejected by him, He keep saying I'm tired, not now, headache, not in the mood,etc... I asked him if I can replace his lifeless libido and penis by getting myself a sex toy to release some of my frustration. He got offended and said it's not healthy and that it's very offensive and disrespectful toward him. I don't know what to do :'( I'm so sad I'm a young woman (27) and I want to enjoy sex while I'm young, and not drooling on my clothe and readjusting my denture. Feeling so depressed.