Is it allowed for me to participate in competitive swimming where the men and women are not in close contact to each other and no forbidden act is taking place, and there is no other option for me as in the West all places are mixed?
To be in a place of competition of swimming with women itself is not permissible for Muslim man. Obviously swimming dress of women in the West is un-Islamic and we can not look at women with out full Hijab.
You should save yourself from such places where you look at women with out proper Hijab.
Wassalam.