There's no way to predict what will happen to you when you're on HRT, I'm afraid. There's no observable pattern as to who gets big loss of libido/erectile function and who doesn't, it's a total lottery. So you'll have to weigh up for yourself how strongly you want to feminise your body, and why, against how strongly you want to maintain your libido, and why, and make a decision based on that.
It's worth mentioning that a very high testosterone level may also be the thing that's driving your strong desire to maintain a strong libido! So one option is to go on HRT for a few months (it remains fully reversible for 3-4 months before you lose fertility permanently, and so on) and see if your feelings change once your hormone levels do.