I like a person and I purposely worked with them to have a part of them inside me.
I want to know why you like that person.
I want to forget all of my sadness
While it's good that you like someone, it's concerning that the reason why you like them is to forget about your sadness as relationships should be built on a solid foundation. You shouldn't get into a relationship in an attempt to get someone to cure your depression. Instead, you should first work with a therapist to be able to stand on your own and be a good partner.
This seems like a much easier way to be happy than going to therapy.
While that may be true in the short run, therapy will help you solve these issues you're having for good.  Therapy will lead to much greater long term happiness for you!