"He's really unhappy at the minute because I won't do them and says it's making his life miserable and I should want to do things to make him happy."
And you're really unhappy at the minute because he won't stop asking you to do things you don't want to do, and it's making your life miserable and he shouldn't want you to do things that make you unhappy.
You are just as important as he is. His behaviour seems to be saying he doesn't think you are important at all, and that you exist only to serve his desires. (Note - desires. Not needs. Desires.)
"My feelings have totally changed and I've tried to explain but I feel like I'm being selfish tearing out family apart when he hasn't actually done anything wrong."
Yes, he has done something wrong. He is coercing you into sex acts you don't want to do. That's wrong. He's emotionally blackmailing you. That's wrong. He's got you believing that you are being selfish when it is he that is the selfish one. That's wrong.
"I just feel so disinterested in him completely, it sounds awful but I feel like we are more like friends than anything else but he doesn't feel the same so it's really difficult."
You are no longer in love with him, and it's not hard to see why. And as for 'he doesn't feel the same' - no, he doesn't. You don't want to have sex with someone you don't care about, whilst he does want to have sex with someone he doesn't care about. I'm sorry 
, but he doesn't care about you. He just cares about getting his end off. He just wants to ejaculate and use you to do so.
"He thinks I'm on a power trip saying no because I'm the only one who can provide the thing he wants. Everyone else apparantly does it so he says after doing some googling."
This is the exact same as telling you that you are selfish and you are tearing the family apart, when it's the exact opposite. He is selfish, he is tearing the family apart and he is on a power trip. It's even got a name, this behaviour. DARVO. Deny, Attack, Reverse Victim and Offender. So he Denies (being a selfish prick), Attacks you (with accusations of being a selfish prick), and Reverses the situation so that he's the Victim and you're the Offender. It works quite well, as long as the actual victim can't see what is happening. As you said earlier, "I feel like I'm being selfish tearing out family apart when he hasn't actually done anything wrong." You've been DARVO'ed. Look out for it next time he presses you. And tell him what he's doing. And don't fall for it.
"He's never been like this before, I can only assume he's feeling hurt because of me suggesting I might want to end our marriage and so he's lashing out."
New behaviour? I wouldn't assume he's hurt, I'd assume he's acquired an online porn habit. Because "Everyone else apparantly does it so he says after doing some googling." Well that's what he's been googling. Porn.
And the reason you're suggesting ending the marriage is his total disrespect for you, his coercing you into sex acts you dislike, and his making your life a misery. All of which have led to your feelings for him having "totally changed".
"Should I just put up and shut up once in a while or is it ok for me to refuse to do certain things? My drive at the moment is through the floor which isn't helping and I have been having sex even when I don't want to just to keep the peace."
No, do not put up and shut up. If you do, your sense of self-worth will take a nosedive and you'll feel even more miserable. Yes, it is OK for you to refuse. Your drive is through the floor because of his demands - it's nigh impossible to feel turned on when your partner insists on something he knows you dislike. And I think you know the word for sex you don't want.
I think it's time you did get out of this marriage. It's dead in the water already, through his behaviour. I think you'll be a lot happier without him.