In the Ved Sanhitaa, God has been described through their powers. These powers sometimes have been referred to as a Divinity and at other times as Bhagavaan (God) Himself. In the Ved Indra is the most important deity representing God. He is the in charge of atmosphere, weather and clouds. He decides the rainfall. More hymns are are addressed to Indra in the Ved than any other deity. He is the King of Heaven. His wife's name is Shachee. Both Shachee and Shakti, in Sanskrit language, mean power.

Later Shiv and Vishnu gained importance and Indra lost his place. When Hindu culture saw its downfall during 6th century AD and 20th century AD, the literary contributions became vulgar, and Indra became a subject of ridicule and humiliation. He was depicted as a coward and a lusty person. He was connected to Ahalyaa - Gautam's wife.  Gautam had found out this and gave Shaap to both, although Ahalyaa was not at fault.

It is hoped that, one day Hindu will realize these stories added to Indra's name as false and will not allow them to circulate any more. Most Hindu are not aware of such stories and they name their children Indra more than any other name. In some Hindu communities, from Bhaadrapad Shukla 12 to Aashwin Krishn 4 is exclusively dedicated to the worship of Indra. He had killed Vritraasur (the demon of drought) also.
(Aangiras, p 69-70)

My Note -
I do not challenge Aangiras Muni on Indra's this issue, but not only Ahalyaa's story is added to Mahaabhaarat, but many other stories are also found related to Indra in our Puraan. Ahalyaa's story is only one, but from that story several other happenings have also taken place, so I don't think that it is possible to make up so many events to insult him. I do not know when Mahaabhaarat was written, it is said that it was written before its events took place, if it has happened so, then Vaalmeeki Raamaayan was written even before that - rather it was written before Raamaayan events took place. Even Vaalmeeki Raamaayan describes this event in great detail. Thus it cannot be said that Ahalyaa event was just an addition to Mahaabhaarat.

[According to [Bhaagvat Puraan, 5/6] There are four Lokpaal (Lord of Direction), one for each direction.
In the east of Meru Parvat is Indra in his Devadhaanee Puree,
in the south of Meru Parvat is Yam Raaj in his Sanyamanee Puree,
in the west of Meru Parvat is Varun in his Nimlochanee Puree, and
in the north of Meru Parvat is Chandramaa in his Vibhaavaree Puree.