I dont know how much you want to hear or face-but youre looking for something I think you already know the answer to...
Heres my opinion only: First your boyfriend has NOT let go of her-if she hadnt had this stroke they may still be together. Im not saying he doesnt love you-obviously he does carry some feelings for you-but from an outside view here hes holding on to HER.
His friends are right-he shouldve let go of her a long time ago and moved on-but for whatever reasons has not been able to-hence youre in the second fiddle situation here and will be as long as you allow it. You either have to tell him this isnt working for you because of :list your reasons and hope he'll move on without her OR YOU make the decision yourself to end it. IF you cant be NUMBER 1 in his life-then you might reconsider just how important you are to him.
Isnt that a huge RED FLAG to you that he STILL brings her home???? He hasnt let go of her or them. Youre there for other reasons-personally I wouldnt have that-its fine to be understanding and compassionate but youre being walked on...and used.
I dont know what else to say in this-because Im NOT in your shoes...it must be difficult seeing you love him-but are you really truly happy?
everything happens for a reason...beginning to wonder why.