A stepfather or stepdad is a non-biological father figure who is married to one's parent. A stepfather-in-law is a stepfather of one's spouse. The children of the stepfather-in-law would be the person's stepbrothers-in-law and stepsisters-in-law.
Yes, your marriage is valid.
Your stepfather has no say in your marriage. If you were virgin (first marriage) you needed permission of your biological father if he has not removed himself from your life.
Even after marriage, if your biological father who looks after you agrees, the marriage is valid. In any way, according to what you have written, your marriage is valid.