Welcome back - and thank-you for it not being a whine.
When you set a route, the invaded systems - or impacted systems - will show in the path as an inverted triangle. Worth checking which entitiy, Triglavian or EDENCOM, hold the system. https://kybernaut.space/invasions - though you can also see that through the Agency window in game. The gates into those systems have Triglavian language markings (triangle script) rather than Empire/System markings.
If you have positive standing with EDENCOM, Triglavians will attack on sight and vice versa. Even if that standing is 0.01. And as you’ve seen they are very aggressive.
The best way to avoid losses is to avoid the invasion systems - given that Nairja on the Amarr-Jita pipe fell to the Triglavians that can be awkward. However I believe a cloaky fast aligning covert ops exploration ship can get in and out of occupied systems with care. If you find an NPC gate camp, wait in gate cloak as long as you can - the NPC fleets move around quite swiftly and you may find they “go away”.
However, we do know that the Invasion is coming to a head - definite signs of the jump-gates into Triglavian Systems being destabilised and potentially about to off-line, the stars in the occupied system are now being heavily disrupted by Triglavian stellar manipulation devices - I suspect we are going to see a cataclysmic event fairly soon that will likely have shock waves across New Eden (what’s the betting it disrupts mineral distribution somehow?).
Things move on in New Eden - one of the delights of Eve: it evolves and you have to keep adapting to the changes. Have a look at the Abyssal Deadspaces - it may be something that interests you.
You are returning in interesting times. Happy hunting and good luck.