If the issue includes gender presentation repulsion, then just start with dressing femme and see how it goes. If you share similar sizes, try wearing her clothes. Have her help you with makeup and outfit planning to make it a fun activity. It will allow you to see if you like it, and her to see if she is comfortable with it.

If the issue also includes genitals and you're planning to change yours, then bringing in someone with those genitals is likely going to be necessary if you want to know before your surgery. A decent quality escort might be a good option to avoid hurting someone else's feelings in all of that depending on the laws in your area or your ability to travel somewhere it's legal and safe. Another option might be some toys that have a full torso with breasts and vulva/vagina and playing with that to see how it goes, but not sure how effective that is overall compared to a real person, which is definitely a different experience.

Also, note that a lot of these things are learned rather than instinctual. Especially gender presentation which is a societal norm, not an inherent gender related compulsion. So, those are usually possible to overcome, though therapy may be required. Genital attraction is a little instinct and a little societal, so it can be more complex. But there are ways around it, like toys.

Either way, a good therapist that specifically has experience with transgender issues is going to likely be necessary because a lot of these issues are not going to just disappear on their own. Usually they are deeply seeded in conditioning from religion or other conservative ideals and breaking those kinds of conditioning takes time and doing it wrong can result in resentment.