Why is it so difficult to grasp the plain reality of things? Militarily BD is no match for India. No one sells 5th gen fighters unless you make one of your own (Highly doubt it for BD) or you buy one by paying the entire research cost (Also not possible for BD)
What do you thing stealth will make your planes invisible? It will only reduce detection range. Once detected, it needs support fighters to protect it, alone it will be taken out.
The reality is, try as hard as you can, you cannot win this race. Hell, Pakistan, which spends 50% of its budget on military for the past 60 years have not matched India conventionally. Nukes are their ONLY insurance policy, for BD sadly, that ship never arrived for them, forget the fact that it sailed away. Try acquiring one now and you will be placed under so many sanctions that you will not have gas to cook your Hilsa fish
In today's world, if you don't have nukes, you might be as well be walking naked in a gun fight. Having an armor (4th gen fighter, subs, tanks) only delays the inevitable, it does not eliminate the threat.
So save your money and spend it on making your country better, or else, you end up like Pakistan. Broke and negotiating in the world with a gun pointing to its own head