Sister in law sending mixed signals

For the past two years my relationship with my SIL took a turn for the worse. We went from being close to her ignoring me, avoiding me and excluding me from hangouts. To be fair I did turn down an opportunity to camp with her and her husband two summers ago, because my husband and I were newly weds and wanted just that weekend to ourselves after weeks of being around family.

It made no difference. She would get her feelings hurt and would give me the cold shoulder afterwards, for months on end. It’s hard to get her to talk sometimes, she’s just a very private person.

I have confronted her about it, but not in an aggressive way. I’ve approached her a few times and told her that I wanted relationship with her still.

All of last year she did the same thing because I got pregnant before her. She wouldn’t talk to me, wouldn’t include me in things, wouldn’t even acknowledge me if I was in the room. But still I initiated conversation with her and she was still short and cold towards me. My husband told me she would complain to him about me, and that’s what got me. I didn’t really want to take offense, but I wanted to distance myself from her.

I couldn’t make her like me, that’s not how relationships work. So I gave her space and chose to move forward. I’ve started hanging with other girls and spending my time with those who build me up and are positive influences.

But now my SIL is suddenly acting like she wants to be friends again, now trying to get close to me like we were before. Unfortunately, I’m still hanging on to some major hurt from these last two years.

Should I be friends with her again as if nothing happened? Should I befriend her but just be guarded? Or should I stay away?