HELP I don't understand

I'm 10 weeks pregnant and my husband has a problem maintaining an erection while we have sex. I've been having to let him watch porn to get a hard on. I feel like shit! He never wants sex anymore I feel like he isn't attracted to me at all. We've had problems before I was pregnant too with this sex crap. I also have to beg for sex and he always rejects me. But yet I mention porn and he gets hard. But he has to continue watching it while having sex with me or he loses his erection!! I'm not fat and I'm a pretty hot girl and we love each other so what is it?? He's 55 I'm 32.