I am sorry for all of the terrible things you were forced to endure.
Your therapist is absolutely correct, sexual abuse doens't "make" you gay or bi. Sexual abuse, however, can create a "same sex attraction."
Whether you are attracted to males, females or both as potential partners for a long term, emotionally satisfying and committed relationship can be answered at a later date. You may need to explore yourself in therapy for a while and perhaps explore having a relationship with a male and a female before you truly know where your heart lies.
I am concerned with a few things you said.
First, I want to make it perfectly clear that I am NOT
The friend with whom you are living is in a relationship with a woman. He has expressed love for you, and has encouraged you to be sexual with him. For whatever reasons (fear, anxiety, etc.) things didn't go as planned, so the following night you tried to be sexual with his girlfriend....
This situation is only going to result in you being hurt. One of the two is going to get jealous if you are in a relationship with the other. It is human nature. It is also coercing you to be sexual, which is very detrimental to you.
While they may be trying to help you find yourself by letting you experiment with them (if that is what is actually happening), that situation is still fraught with difficulties.
Loving your friend because he is showing you kindness and acceptance and he is giving you and your son a place to live does NOT mean you have to "pay" for that with your body. Please read the thread Sex As Currency.
I suggest you speak to your therapist about this. Obviously you have a lot of trauma and confusion from the abuses you endured. Right now might not be the time to be sexual, with anyone, other than yourself.
And when the time feels right for you to be
sexual, it would be in your best interest to find someone to whom you do not feel you are obligated to pay with your very being.
Abuse, in all of it's forms, damages our abilities to recognize relationships that may or may not be healthy.
If you want to show your friend you appreciate the things he is doing for you and your son, find non-sexual ways to express your appreciation.
It is not up to your friend to tell you who or how you love, nor is it his right to make you figure it out.
Check your local area for groups/ associations that are GBTQ focused and get involved in activities. This will give you the opportunity to socialize. GBTQ centers typically run a variety of groups and social functions. They are also great resources for support.
You were forced to be sexual at a very young age, and the natural exploration and curiosity was taken from you. It is understandable that you have questions and confusion.
NO ONE has the right to force you to be sexual now, nor tell you to whom you are supposed to be attracted.
Despite the fact you love your friend, you cannot say "I Love You." The love you have for him may not be the same as being in
love with him. Perhaps saying those words are just too terrifying. Whatever the reason, you are not obligated to tell anyone you are in love with them, either.
I am sorry that your friend got angry with you.
It sounds like he has unfulfilled needs. But he cannot demand that you fill them, at your expense.
What you need now is a friend who will give you the opportunity to heal from what was forced on you and the time to discover your choices.
Be gentle and kind to yourself.