What's done is done.
You can't change the past.
You do have control over your future, however.
You will always meet some people who would judge you for your past actions, but we all would. MN is as good as place as any to demonstrate that people think very differently from each other. However, you've managed to create a thread filled with compassionate replies and that should tell you something.
You are not responsible for your child growing up without a father. Yes, you made a selfish choice and plenty would condemn you for it. But I guarantee you do know others who've done the same, they're just not brave enough to admit it.
I know someone who did the same.
The only person responsible for your ex's relationship with his child is him. No contraceptive is 100% infallible, so whenever a man chooses to have sex with a woman he, like the woman, is accepting there is some risk of pregnancy.
Assuming he knows about his daughter, it's been his choice to disown her. Very easy for him to blame you, but some men are excellent at deflecting responsibility.
If he doesn't know about her, then you still have time to make it right. Reach out to him and offer the opportunity.
As for friends. Plenty of people reach 40 without close friends, there are any number of reasons why people drift from uni and school friends. You have the rest of your life to make true, worthy friends.
You can still build a relationship with your sister. The key to is being honest and also being open about times when you may find it overwhelming to keep in active contact. If she's precious to you, though, tell her. She wants to hear it.
So do three things: Please do have therapy and learn to forgive yourself.
Reach out to your sister and your ex.
And promise me you won't accept bad treatment in friendships or romantic relationships out of some misguided belief thar you deserve it.
Your future is yours to create, let go of the past and start being excited for all the wonderful things waiting for you.