Brother Sperm- Weird, or Not Weird?

DH hadn't really talked to his anyone in his family about our situation except for his parents- he was fine with them passing on the info, but I think he was still too stunned, sad, etc. to actually talk to his siblings about it himself.  Well, he talked to his sister and mentioned the idea of embryo adoption we found out about.  DH's sister asked if we had considered DS- he let her know that he didn't think that was right for us.  What she told him next really mixed things up for us.  She said that DH's brother had told her that if we wanted to, he would without hesitation donate his sperm to us.  Wow...  My first reaction was an uncontrollable sob- what a selfless and amazing thing to do for your brother!  We are so far away from even knowing if we would go this route, but to know that he would do that for DH really touched me and will forever change the way I think about DH's brother. 

I assumed that DH would not want to do that because he had seemed so opposed to the idea.  He said however, that he was actually very open to the idea (I mean, I was TOTALLY not expecting that).  He and his brother look very much alike and he loved the idea that our child will resemble him physically, not to mention that if their are any medical issues with our child, we would have both biological parents' history.  This has totally shaken things up for me.  If it comes to us not being able to conceive on our own, I really don't know what I would want.  It seems like the more options I find out about, the scarier the decision becomes.  I love the idea of the child being biologically linked to DH, but will DH ever come to resent that his brother was able to give me what he could not?  I certainly don't think of it that way, but the hubs has been so very hard on himself throughout this whole process.  I also ask myself, it it weird if I become pregnant with my brother-in-law's sperm?   If it comes to this decision, how will we ever make the right decision?