India and Pakistan will not be sending a nuclear bomb your way dont worry. But there will be radiation clouds and weather patterns not only in the region but whole world (Assuming case where 0 pre-emptive targetting + interception happens and worst case scenario of all cities targetting).
Not to mention if the targets are cities, you would create massive firestorms and soot that cause global cooling (maybe even a short ice age) that is going to affect the whole world. Some models have projected as little as 50 warheads used on cities anywhere in the world, would create drastic temperature decreases (validity of course can only be proven by actual situation manifesting) based on mount pinatubo explosion and other such events (where data gathered in stratosphere and correlated to world temperature)...that would probably cut world food production by half or more (and you can imagine what that does to world population).
Indian BMD actually would protect Bangladesh automatically too, because all trajectory vectors in realised launch and apogee phase are very similar for Kolkata and BD (orginating from Pakistan)....anything with BD as a target simply must be intercepted by India...because it cannot be distinguised as different from Kolkata+Durgapur/Asansol heavy industry hub etc till its in final terminal phase (and much harder to intercept anyway). If BD stays in decent enough relations with India, you can piggyback off pretty much for free for BMD protection. Its early days of course right now...much technology needs to get matured....and BD will also be much larger economy by then, so I guess lets see. But India will not be using any nukes on BD (as pyrrhic destruction or otherwise like what Soviet doctrine had), we simply destroy more of India doing that, you are right next to large population centres of ours....and you do not figure in our MAD doctrine given you are not a nuclear power anyway....and we have limited warheads in the short and midterm anyway for propping up the MAD strategy with our major two adversaries (their cities and targets are the only ones of relevance for us).