Boyfriend rather look at porn than have sex with me but he wont even watch porn with me i ask to

Hi ive been with my boyfriend for almost 3 years now. A year into our relationship i found out that he has been having an affair since pretty much when we started going out. We had been living together for a month at this point as you can probably imagine, i was devastated. I decided not to leave him for i had still loved him and well to tell the truth im not exectly got the highest of self confidences and that i know i'm not pretty as i've been told by my mother and still get told now that i'm not thin enough or dont dress girly enough and i was just a UK size 12 at the start of my current relationship but i'm top heavy so that didint exactly help with my confidence so i was also terrified of being alone knowing that i would spend the rest of my life alone as pathetic as that sounds. For now i will go further back. When i was a child i was sexually abused by my step brother for many years. After that i have different veiw on sex and how i veiw men and has cause problems in all of my relationships. I have only told my current boyfriend about my past. Anyway after finding out about the affair i have lost ALL of my self asteem and trust in him and men. Then over time i started to find out how much porn that he looked at as i didnt even think about him watching before. I asked him to stop watching it. He understood why i asked him to stop but that would last about a week now i still ask him to stop it as it really hurts me plus i have a very strong veiw on pornograghy. Its just a word to make prostitution okay and that is not acceptable. The last time i caught looking i offered to watch it with him and for some reason he wouldnt! he's said to me that he feels ashamed watching it, not because of me but just in general. oh yeah if you were that ashamed you wouldn't do it! We have never had the most active of sex lives but we used to do it once or twice a week but now its disapearing all together. I've told him how i feel about this and all that happens is that week consists of us having sex twice a day over 3 days then nothing for two months and all the time still watching porn. At the start just a couple weeks i found out he was having an affair i tried dressing up for him in sexy outfits but he wasnt even interested. Since then i have have gained wegiht. He says he likes my size but i think he's just saying that to make me feel better. Now when ever we do have sex i can't bare to take my top of. i've asked him what his fantasies are and he says that he doesnt have any just stockings he likes so theres nothing i can try and do now to spice it up also even if we do have sex its just all about him, him, him, just him getting the pleasure. I just feel hurt and humiliated. I'm now about to start ant-depressants i just cant handle this any longer but i dont want to leave. What should i do? in desperated need of help. btw were pretty poor so we cant afford counceling.