Does unintentional urine retention, which causes a feeling of lust, necessitate ghusl if it results in discharges, and are my prayers valid in this situation, and am I sinful for unintentionally retaining urine without the intention of arousing lust?

As long as you do not intend to arouse lust, there is no sin upon you. However, it is advisable to abandon this act due to its negative impact on health. What is usually discharged is wady and not maniy (semen); wady is impure, necessitates istinja' (washing the private parts), but does not necessitate ghusl (ritual bath). Your previous prayers are valid. Maniy (semen), which necessitates ghusl, is discharged in spurts with pleasure and is followed by a weakening of the body. Continue to resist and rid yourself of waswas (whispers from Satan).