Well, handing him an ultimatum will take the pressure off!
Sorry, I know it is really frustrating and I totally understand, trust me.
First, you MUST stop blaming yourself flowermaid.
Second, you need to calculate what percentage of your marriage is sex. That makes it seem less catastrophic.
Third, you two need to communicate
how to "have sex" without penetration from HIS penis, since obviously his smaller brain is not cooperating.
Trust me, he isn't happy about it either and the MORE pressure he feels, the less likely things will get better. It kind of puts you in a catch 22 situation, and it sucks big time, I know.
There ARE other things to do that can make sex good, you just need to be creative. I know it is nice to have a nice, hard penis from dh ALL the time, but when it isn't working you have to use substitutes.
You are not the only woman in the world this is happening to. I think of it this way: would you rather it be YOU in YOUR dh's position? Try to put yourself into his shoes, you love him, so you can imagine how BAD he must be suffering.
PM me and I can give you details about some methods to help.