Should I contact my long lost adult sister who has cut contact with ALL family members?

20 years ago, my sister moved out on her 18th birthday during midnight without notifying my parents leaving a letter on the bed stating she's not kidnapped and not to contact her again The same day when it was afternoon, we got notice my sister was adult adopted. With the help of a private investigator, I have found her and would like to contact her and form a relationship with her but I'm afraid she's going to place a restraining order against me. Here's the letter she wrote:

Dear (recipient)

The purpose of this letter is to inform you that I am not missing and/or kidnapped and I no longer wish to contact ANY family member including but NOT limited to siblings, parents, grandparents, aunts, uncles, cousins, etc. Do NOT contact me for ANY reason including but not limited to inform me of death (anyone's death), to inform me the news, to see my children/to see if I have children, to see if I'm married/who I'm married to, and to see how am I doing. Do not contact me through physical presence, electronically (phone, internet) and through friends. Do NOT look for me and please ask ALL family members not to contact me. I no longer see you guys as "family" and just because we are biologically related doesn't mean we're "family." Do not blame anyone for my abandonment including but not limited to with these phrases. "It's your fault why she left," "you did this" "you did that and that's why she left." Please do not argue over me about me disowning the family.