Can psychological trauma become worse if not dealt with correctly? by that i mean, can symptoms get worse and can more mental illness develop?

Yes: If the trauma is really significant it can stay with you over time. It may lead to avoidance of certain situations, ^ anxiety, problems w sleep, ^ arousal. Some people may develop a condition called post traumatic stress disorder. It is best to accept professional help if you are struggling with past trauma.

Different: People deal with psychosocial trauma differently. It depends on your coping mechanism and if it is a healthy one. Some people can go through trauma and forget about it and not let it affect them, while others try and can't do so and it affects them in different ways. See a professional such as a psychiatrist who may be able to guide you with appropriate treatment options including therapy.