Pretty much.I believe Tegan is dead However, it's an interesting case because if she had done something like leave Tegan in the bush because she couldn't cope or admitted to infanticide almost certainly she would have served her time by now. I don't think she did. But I do think she felt trapped because she was made very uncomfortable (I'm wondering if she was accused of using abortions and adoptions as contraceptives) with the previous adoption and didn't leave any option other than keeping the baby until the baby was born. Whether it was the shame she thought it may cause her family or end her relationship (and cause further shame) if her boyfriend found out, that she was desperate and asked her Dad to help out?
She would not want to ever address what that may have entailed and has lived in fairy tale land ever since. But she does realise that if this was what happened and she did tell the truth, she would be destroying all in her family. I don't think she ever thought she would be convicted and didn't realise the pile of lies would get her where she is.
Saving face (in your own mind) can be a very, very powerful motivator. I think she ran the gauntlet with police and the courts and has been too deeply ashamed to ever admit it. And she never will, IMO.