Whenever I decide to leave a sin, my old friends and environment pull me right back in. Is my tawbah doomed if I can’t change everyone around me?

What you describe is a real struggle, not a failing. You are trying to rise, and each time you rise the old current pulls at your feet. That is not a sign that your tawbah is doomed. Only the one who climbs ever feels the weight of the slope.

The Prophet (peace be upon him) told us of a man who had taken ninety-nine lives and then a hundredth, and who still wanted to return. The wise man he turned to did not tell him his past was too heavy. He told him something about his surroundings.

“Go to such and such a land, for there are people worshipping Allah there. Worship Allah with them, and do not return to your own land, for it is a land of evil.”

The Prophet (peace be upon him), Sahih Muslim (2766a) · meaning

Notice what he was not told. He was not told to reform every person in his old town. He was told to change the soil he was planted in, to walk toward people who would water the good in him instead of trampling it. You are not asked to fix everyone around you. You are asked to lean, little by little, toward better company.

Company shapes us the way water shapes a stone, quietly, without our noticing, until one day the surface is different. That is why the Prophet gave us this instruction.

“A person is upon the religion of his close friend, so let each of you look at whom he befriends.”

The Prophet (peace be upon him), Sunan at-Tirmidhi (2378) and Sunan Abi Dawud (4833), also Musnad Ahmad · meaning

So do not measure your tawbah by whether the whole environment changes. Measure it by the drift of your heart toward light. Keep your old ties with kindness where you must, but let your closest companionship gather slowly around those who remind you of Allah. You do not need a hundred new friends. Even one sincere companion who pulls you upward can, by Allah’s leave, become the land of good people your soul has been looking for.

One small step: Reach out this week to one person whose company softens your heart toward Allah, and make a small plan to sit with them regularly, even if only for a short while.