から there is not "because" but indicating the direction ("head-on")
All of「こいつと正面から向き合っていれば」is a condition. (If I had faced him head-on...)
Because the second half is past tense (未来は違った) this is what is sometimes called a "counterfactual".
That is, the conditional part didn't actually happen. If it had happened, the future would be different (well, かもしれない = might be different, as you correctly translated). However, it didn't. のに indicates the speakers regret at this.
Another common pattern that you might have seen is ~ば form + よかったのに (It would have been good if/I wish that/you should have/etc).