I just wanted to drop in some big HUGS its a tough, tough situation.
I would personally offer lots of hugs and comfort. Although it will be tough as he will still be able to smell your milk, can your partner also offer some comfort? Now you've started down this road I would just stick with it if you've got a pressing reason to wean. FWIW my friend went cold turkey like this, it took her nearly a week before her baby would have more than a few sips. She was amazed at how her baby would still sleep etc. after not drinking much.
Despite my baby taking it earlier on she went off it and I ended up hiring a maternity nurse who had a special knack. I'm sure you've been told so much already I did all the research under the sun looking for the magic answer! but FWIW I know how horrible this is and just have to share some of what ending up working for us in case you find any of it useful - we used a narrow neck straight up and down nipple, like from a evenflo bottle, she was less able to push this out of her mouth compared to a breast like, flexible nipple like avent or tommee tippee. We held the bottle like you would hold a dart so your first two fingers are holding the bottle and your little finger can then hold firmly under their chin. Although they are heavy at this age if you are able to hold baby firmly like in like a rugby hold with their one arm behind your back with their head quite firm between your body and arm to avoid them thrashing their head around so if poss you can walk around with them.
Distraction is key so if you can walk around with them like this show them anything new & interesting, sing, anything to take their mind of the bottle & get them to start drinking without thinking. Jiggle them a bit too if necessary. If possible just hold bottle firmly in their mouth with the method I described above and if they're turning their head etc. just turn with them but try not to take the bottle out unless they're really really upset. Use a nipple with a flow that matches yours at this age I would have thought fast flow so its easy for them. And don't keep changing bottles just use one and stick with it. Although some people say its best to have someone else give it, I actually found I was better she knew me best & was actually most relaxed with me.
If you want to or are able I was told using expressed milk makes an easier transition ie first get them used to the bottle with BM in it, then once they are used to the bottle start mixing in the formula - this is what we did. So they're not trying to get used to 2 new things at once. If this isn't possible/feasible don't worry.
Biggest hugs, let us know how you get on, we're all here for you.
