My fiance (M19) has been choosing hentai over me (F18) and I dont know what to do

Weve been together for a almost a year now, just recently I had woken up to him touching himself next to me while I was asleep. He hid his phone from me and looked emberassed which is something he usually wouldnt do. The last month or two he has barely touched me, and ive been trying super hard to get his attention. Ill shave my full body, do makeup, ive been getting different lingerie and it doesnt work. I mean we live together and he comes home to see a half naked women infront of him basically begging for him to just do something with me. I asked if I could see his phone after I had waken up fully, I was freaking out because I knew it wasnt me that he was doing it too and it was only 4:30 in the morning. He told me what was on his phone was still on the screen but I took it and I opened it and it was drawn on images. He tried to explain to me and I just told him to leave for awhile. His only explanation was that it felt ‘less like cheating’ I mean I was devestated, ive been crying almost every night because I thought he had lost interest in me, less talking, less sex, less everything. It wasnt normal for me. Ive tried talking to him if he wants me to try new things and he always shrugs it off or tries to say he still loves me. Im a stay at home for right now because im going through schooling programs trying to get a degree so I thought maybe he had met someone else but he never talks to anyone when hes home. I talked to him over the phone for maybe an hour beforehand and I asked him to come back over to our house before we continued talking because I wanted to hear him say everything in person. He said everytime we shared sexual encounters hes felt emberassed because im mean to him afterwards or quiet, and that its because he doesnt last long enough for me. Apparently the images dont make him feel that way. Ive told him several times I dont care about his performance and quite frankly the only times we do get it on I have to really pursue it otherwise it wont happen. I felt really hurt after hearing this because of how much effort ive been trying to put in with him. And I dont think any of thats true. Ive tried telling him I love him and I show it everyday to him, I wouldnt want to make him feel uncomfortable about his performance. I asked him how often he was watching these types of things and he told me it was only every week or two. I then asked him the question of how often does he touch himself to me, he answered it 4/10 of the times. I felt heartbroken because when he does these types of things he locks himself in the bathroom and I realized this didnt start just recently, and that hes been doing this our whole relationship. I dont know what to do honestly, I send him new things every week and I try to encourage it to go onto more than just me sending him things but it never happens. He told me he wouldnt watch or do this type of stuff anymore but I dont believe him and that hurts for me to think about it. After we made up he wanted to have sex with me and we ended up doing it. He went to bed and then went to work right after waking up. While he was at work he texted me saying he wanted to try something completely different ive never heard him say to me. And when he got home we ended up doing it. Usually we stay awake for a few hours, eat dinner, watch a movie, talk. None of this happened after he got off of work, he went back to bed. And then just this morning he wanted to again. Hes at work but before he left I told him I didnt want this relationship to be turning into something different, and he told me I either get the sex or I dont, and that if we wanted to we could just go back to me thinking I wasnt attractive enough for him. I dont know what to do with any of this and I would never go online to ask but I dont have anyone to talk to about this that isnt biast. I mean this really hurts for me to find out. I guess the only thing I want to know is if he would actually stop. And I dont even know if it makes me comfortable if he stops because it feels dirty having sex with after finding this out. I mean he chose drawn on images and videos over me for 2 months and hes been doing it our whole relationship. When we first got together I told him I didnt like this type of stuff and that I still thought it was cheating in some form even regard it being not an actual person, he told me he wouldnt do it and now this is happening. What do I do?