Smoking

I'm 19+3 and on day 5 of not smoking at all. I cut down in the weeks leading up to this. Anyway I'm REALLY struggling today. Big time. I tried explaining to my partner how hard I'm finding this and he just replied with 'well the damage is already done you've left it too late to quit' and walked out the room (he's a smoker). I know I should have quit the day I got my bfp but I physically couldn't no matter how much I wanted to. I thought quitting now at 19 weeks is better than not doing it at all and smoking til I give birth, but maybe I'm wrong? I'm in such a state about this and feeling so guilty 😣 
I guess my question is, do you think quitting now will still have benefits to my unborn child? Or is it really too late?