Is this gaslighting?
My partner has cheated on me in the past and I forgave her after trying to work through it and understand why. But she does not seem willing to help me feel good about the relationship now. Say I won’t be able to contact her for a day and she will say her phone died and it’s not a big deal and almost makes fun of me for thinking something else is going on or she will say she feels under investigation when I just ask of her plans. Is this gaslighting? I just want her to see how things effect me and I trust her but think I’m stupid for it.
The short answer is: yes, she is gaslighting you. She might not currently be cheating on you (and she might be), but at the very least she’s inconsiderate and unremorseful. At worst, she’s intentionally trying to hurt and belittle you.
Either way, my wish for you (and for everyone) is to find someone who is capable of treating you with respect and consideration. You say that you trust her, but do you? Should you? Betrayals of trust might be an isolated incident. I believe in forgiveness and making amends. However, it doesn't sound like she is making amends. She sounds callous.
Everyone makes mistakes and obviously I have no knowledge of the circumstances under which she cheated. But based on what you said it sounds as if though she doesn’t genuinely care about nurturing the relationship and doing her part to heal the pain you felt as a result of her cheating.
You deserve someone who will treat you with kindness and respect and who never, ever belittles your emotions. Don't sell yourself short here - forgiveness doesn't mean staying in a relationship where you're treated badly. Whatever you decide to do, I wish you much luck and love.