Am I wrong?

My husbands family is driving me to the brink of insanity! His brother I ended up blocking his number because I can not listen to him anymore. Everytime he visits or calls he is drunk beyond control and he starts babbling that he can't loose his brother, he would have to step up and raise the boys, that it's becomng real now that my husband is losing his hair. He proceeds to make up his own illnesses to the point I don't know if it is real or fantasy anymore. He is claimming now the stent in his heart has collapsed and it can not be repaired. I don't beleive this, I barely belive that he has one in the first place. He does not carry a serial number on him that would have been provided. When I asked if he was on blood thinners he claimed he can't afford them, I offered to pick them up for him and pay for them and he responds he doesn't need them with his kind of stent. Sounds like another lie to me. 

He's a raging alcholic, but won't quit drinking. He insists that if something happens he will have to raise the boys then. Over my cold dead body! I have drafted up my will to reflect under no circumstances that he is to get custody. He has been arrested for domestic violence, DUI's out the wazoo and NO he will not take my kids if something happens to the both of us. 

Last night, put me over the top. He called, drunk slurring his speach, and was crying how real it is now that my husband is losing his hair. That he has special blood that could help my husband and that he would take his own life so he can have it. He babbled that he was going to come see us everyday because he needs to spend time, unlike his mother or sister. He was saying all kinds of crazy and depressive things. I told him flat out I am being held together with tape and glue, did not need to hear his sh** and hung up immediatley blocking his number.

I meant it when I said I am being held together with tape and glue right now. Is it wrong of me though to shut his brother out? This morning I feel guilty about it. But I am sick and tired of everyone on his side of the family crying on my shoulders. This is my husband, the father of my children and I don't have the willpower to lend any more support. I can't have his family expecting me to give comfort as I have NO ONE comforting me. Am I wrong? Should I support them emotionally too even though they are toxic?