Feelings for ex girlfriend

James
We were dating for a good two months and I felt like I was in love , she told me she loved me all the while , then out the blue after two months she said " I don't want a boyfriend sorry " , we haven't spoken since properly but the other day our two friend groups were hanging out and she was laughing at my joke and smiling at me , I felt something between us again ... I've had feelings for her all the time after she broke up with me ( she broke up with me like 3 months ago ) ... What should I do ?