Firstly, Bangladesh is a high fraud country, secondly you have a 50 year age gap (this alone is enough for you to be under the microscope at vetting levels), thirdly you have been in a 4 year relationship and have never met even once, furthermore, k1 path is not considered as an emergency to USCIS as you are not considered his immediate relative. Finally I know where you come from people at 74 still work in farms and do a lot of manual labor, in the States, these group of persons are seniors who are at the last legs of their lives and are very fragile (90% of them live in nursing homes, retirement homes, assisted living homes or if they live alone, they have some sort of home health aides). Summary is that your chances of having a life with this man in the States are near to 0% , he needs treatment now and I do not think the weight of immigration should be put on him at this point. My personal advise is for you to move on and not waste another 4 years of your time because USCIS will accept all your fees when filing and would definitely not give two flying flies about the urgency of your case.