Hello friend,
The rules out of the box do permit you to defend with your fighters, but they are not all that effective in stopping gigantic or continuous raids unless you get a really sturdy pile of fighters (4-10+) and then he has to consider whether he wants to risk attacking you with unescorted bombers. The rules as written (1s are rolled for scramblers, escorts, and bombers, casualties taken, then aaa then bombs dropped) are pretty fair if you make sure that you concentrate your fighters and the Global version of the game does give you extra factories and money compared to other versions so choosing to buy fewer units and repair less ironically makes it less effective over time.
Others have argued, that statistically, the risk to the bombers is not $ for $ worth the SB trade, and this is plainly true, but the contrary point is that the bombers are 1) destroying money before it can be used 2) against a nation that is weaker than you so you can take losses 3) can be used any where at any time and not just to bomb AND it ties all those fighters down.
There is a Balanced Mod House Rules (linked above) that changes the rule (scrambling defenders hit at “2”) and makes interceptors more powerful, but this makes stratbombing less useful in my opinion, because the defense is increased vis-a-vis offence and once you get a bunch of fighters its a no-go on the big targets.
So yes, it may seem really abusive and that is just supposed to be part of the game and its a product of having too few fighters left early game, not building enough fighters throughout the game, and, once the USA is in the war, it can fly them over either via iceland or UK carriers, gibraltar etc. Instead of the nearly useless AAA (rarely bought), fighters are the word. If you still feel that it is broken, change to the “BM” rule of scramblers are 2 and escorts and bombers 1. Still, I prefer the basic rules, for most games (and perhaps a bid)–-strat bombing is a two way street and you want both teams to be able to use it generously though it seems a bit overpowered in some situations.
Also, if he is bombing you out like this, the bombers cant be also used to lazer moscow or your invasion fleets, so Germany has to pause these offensives or rethink them as the game progresses b/c the bombers can only be used to overwhelm one zone at a time…nevertheless the bombing is devastating, at least to one of your teams at a time…