Past perfect vs simple past

Sentences:

1. When I heard that you had sold the company to the highest bidder, without consulting me first, I wondered how it was possible that you [had done]/[did] that to me after we had been friends for such a long time.

2. When I heard that you had sold the company to the highest bidder, without consulting me first, I wondered how it was possible that you [had done]/[did] that to me.

Question:

Which tense should be used in the above sentences: the past perfect "had done" or the simple past "did"? Or are they both correct? I also wonder if removing the words "after we had been friends for such a long time" makes any difference in this case. Thanks.