I agree that it's much more likely your current partner's. Advice to get your HCG tested is good & I think an early dating scan will also help. I'd do both of those before thinking about telling anyone anything. You'll have a fairly certain idea who is the father after you've done them, and if those tests confirm that it is your current partner's, then there might not be any need to tell anyone anything. Goodluck & congrats on your pregnancy!