First Latvia was occupied by the Soviet Empire, and all that entails, the purges, the gulags and so on. Then it was occupied by the Nazis, and all that entails, death camps and so on. They were especially keen on punishing anyone they thought might have found a way to co-exist with the previous invaders. Then after that, the Soviets again, keen to punish Latvia for "surrendering" to the unstoppable Nazi war machine. The Soviets were keen on lebensraum too, and set about deporting Latvians on an industrial scale, and colonizing the country with Russians.
They are still finding pockets of exiled Latvians deep inside the Russian interior, and asking them if they want to come home.
The Eurozone (Germany mostly) is getting closer and closer to Russia. I don't think Latvia will gain any advantage from this.
Take a look at what happened to Cyprus. They (the EU) would never do that to Italy, no matter how crisis-striken would ever be. Meaning: Say tomorrow Russia invades Latvia, the EU will do a couple statements and that's about it.
How an attack on a EU member state will be reacted to will set precedent. The EU cannot afford not to react to such an attack with full military force no matter which member state is attacked.
Apart from that the majority of states in the NATO are also EU member states, meaning that the EU has effectively control over the NATO. Also something that might be worth considering in such a scenario.
On the other hand, the baltics are primarily of interest to Russia as a buffer against invasion from the west, so it is at a time of antagonism between Germany and Russia that Latvia would most need to fear Russian invasion.
Latvia can always invoke Article 5 of the NATO treaty, anyway.
