What if my ex is on a destructive behavior after our breakup, and she contacts me because she feels at ease, but if I initiate the conversation, she would tell me to leave her alone?

Sorry to hear you are struggling with your ex. Relationships and breakups aren't easy at all and you're doing an amazing thing asking for support on this situation. I have gone through similar ones in my past relationships and have learnt that people heal at different times during a breakup. Your ex might feel comfortable talking to you when she feels emotionally prepared, but perhaps having contact sprung up on her contributes to an anxiety she may have that then projects as anger towards you, and act of defence if you will. It's completely normal for two people to be at different stages in breakup healing, so you aren't alone! Just being respectful and mindful of peoples boundaries is hard enough without emotions getting in the way. You both are entitled to your peace of mind and healing, I hope it all works out for you. You can be there for her as a friend when she needs you if that makes you feel comfortable, remember it's always important to check in and look after yourself first.