It’s normal to feel attracted to other people as long as it doesn’t go beyond that—it’s not cheating. Maybe it’s also because you miss her and you’re unconsciously looking for what feels “missing” in her in other people. That could also be why you’re starting to feel suspicious now, not necessarily because she’s doing something wrong, but because your own feelings are shifting and you’re overthinking things.
Try to go through your plans first and don’t focus too much on what might happen next. Just let things flow naturally and follow where things go without overthinking every possible outcome.