Her sister invited me to there grandma's burial

My ex girlfriend which we broke up 5 years ago and we both lose communication with each other, 2 months ago her sister reached out to me and invited me for their grandmothers burial because of course myself and the sister were friends too back then and she have gotten my number from a friend of mine. So we talked for a while and I asked her about her sister which used to be my ex girlfriend ‘let’s just call this ex girlfriend Pam’. Pam told her sister not to give me her number that she doesn’t want to have anything to do with me because now she’s in a 2 years relationship and then I didn’t bother her anymore. Few days after, Pam herself Dm me on WhatsApp and I was surprised, we talked for a while and she asked me how I am then I told her I’m a little sick. She sounded caring and decided to come pay me a visit because her grandma's house was close to mine. I taught she was joking but she called me that she was at my junction and I went to pick her up that evening then we came back to my house and talked for a while. I insisted she spend a night here but she refused because she said she doesn’t want us to have anything then later on she agreed to spend the night over. Shortly after her boyfriend called her and she left the room to pick his call in the sitting room lying to him that she went to make delivery and all that. Fast forward to the night she started romancing me and we had a great sex that night and the following morning we also had sex. she began to cry saying she haven’t cheated on her bf for the past two years and that she has made a very big mistake and so on. She told me she can’t continue to live with herself like this and wanted us to come back in relationship but she was willing to break up with him after she claimed she loved him and me too was in complicated relationship at the moment and because of her I broke up with my girlfriend to be with her. Then shortly after her grandma burial she travelled back to her boyfriend place because they live together and she blocked me on WhatsApp so I tried to call her one morning then she picked up and told me not to call her again that she was lucky her bf just stepped out the room when the call came in otherwise she would have been in so much trouble. Then shortly she ended the call end ever since then, I’ve been trying to call that number with different phone but it’s not going through now I don’t know what to do. She ruined my relationship completely and my mental health now. Should I reach out to the bf and do the same by telling him what she did? I need advice.