I am sorry he is doing this to you! I had a best friend who did this to me, and I finally had to tell him that it was bothering me and if he kept talking like that/calling random people fat&ugly/etc. I was not going to hang out with him any more. (i know it is not that simple in your situation).

Does your fiance know that you suffer(ed) from an ED? If he does, remind him that you can only remove yourself so much, and that it would be helpful to you if he kept his comments to himself.

Luckily, he is not your husband, yet. I would definitely make sure that if he is not willing to work with you on this, that you want to continue towards the path of marriage. I am not telling you what to do, but definitely look at your options, and whether the good still outweighs the "bad."

Good luck...keep us posted. Hugs to you.