AITA for encouraging my sister to start therapy when she confided in me that she felt guilty for remarrying after her first husband died?

My sister was with her first husband for 6 years when they got married. She was pregnant at their wedding day and they were so excited to be parents. Sadly the happiness only lasted for 5 weeks because her first husband passed away suddenly after an accident. She struggled with his loss for years and when she had their daughter she focused a lot on her and keeping her connection to her first husband's family.

When my niece was 4 my sister reconnected with her high school ex, they became friends and two years later started dating. They were dating for a few years before they got married. At the time my sister appeared very happy and her daughter was taking it all well. But several years on and she started confiding in me that she has felt guilty for remarrying and especially because she was with him before her first husband.

She told me she had so many conflicting feelings. She had hoped her daughter would start calling her husband dad, or at least tell others he was her dad even if she continued using his first name in conversations with him. But she didn't. And she felt guilty for wanting that and felt like it was disloyal to her first husband and what he would have wanted for their daughter. She told me she hated the idea that she had died in childbirth instead of him dying while she was pregnant and his second chance at happiness coming with her being forever replaced by a new wife for him and a new mom for her daughter. But she said she also felt bad for her husband for feeling so guilty about it and she believes he struggles with his relationship with her daughter and what his role and place is.

I asked her if they'd talked about this and she said no and she would never tell him she felt guilty for marrying him. She told me my niece asked her once if she loved her dad or if he was someone she was with because she couldn't be with her husband. And my niece asked this because they talked about her dad previously and my niece was aware that her mom and stepdad dated in high school.

This furthered my sister's guilt for making her daughter even think she didn't really love her dad.

My sister has talked to me dozens of times in the last few months about this and she expresses guilt every time we talk about this. So the last time I encouraged her to find a therapist who could help her and I told her I did not believe her first husband would want her to be so twisted up in knots about this or her current husband. And I told her I didn't feel like I was able to help. She told me she was afraid a therapist would make her tell her husband everything and she also didn't want to bring up her mixed feelings on him not being dad. I told her it was okay but she could find a therapist who wouldn't bully her into anything and would work at her pace. She told me I was making her feel like shit by encouraging therapy so much and she told me she doesn't see why she can't confide in me, her little sister, instead.

She keeps talking to me but she's tense around me now because I encouraged therapy and now I wonder if that was a poor choice on my part. AITA?