I think im being emotionally and mentally abused by my brother,my dad is very old?

( 97) and has severe alzheimers disease,i am being forced to care for dad when the regular aide isnt around.when she leaves my dad will open the door and take off,i get very angry and call hm in but dad tunes me out and keeps on moving.i tell my brother and he expects me to follow him,he says so what,let him do as he pleases.this is a bd practice because my dad doesnt know where he lives and he doesnt know his phone number or address.to keep dad safe my brother should invest in a medic alert tag,but no,my brother wont have that.he will do things his way as long as he isnt involved with my dads safety.i cannot keep up with my dads growing mental problems which include wandering and lashing back at anyone who gets in his way.hes attacked me on several occasions.the aide says we need a lock change to keep my dad from opening the door and geting out.brother says ok but never does anything.what will happen will be a disaster if we dont curtail my dads insanity.what can be done to get my brother to move on this?