Relocate children 15-20 miles from father & he has filed objection in court. What's my chances of winning?

I am divorced mother of 2 boys (ages 8 and 4). I have owned a home for 9 years and am wanting to sell and move to the country to raise my kids. I have notified via certified mail my ex husband that I would like to relocate 15-20 miles away in the country from where I currently reside. My oldest son would have to change school districts but would still play in the same sports in the community we currently reside. (thru the parks and rec dept) My ex has filed an objection to my move in court and stated the long distance would hinder his relationship with the boys and the change in school would not be in the kids best interest & has asked for physical custody. Well I am only asking to move less than 30 miles away....I don't see 15-20 miles as being long distance. Additionally, if he was awarded physical custoday my oldest son would have to go to a new school regardless because my ex does not live in the same school district that I currently reside in. I have just completed a lot of work to my house and listed it with a real estate agent this week. I would like to sell my house and buy a new house prior to school starting Aug 19th. My attorney has advised me that I do NOT have an order against me stating I cannot move; however, the court could look bad at me for relocating the kids since my ex has filed an objection. Now if I was moving them out of state I could totally understand, but 20 miles, give me a break!!! I totally believe my ex is doing this just to be mean to me as I had numerous restraining orders against him after I caught him in bed with another girl when I was 3 months pregnant with our second child. My ex has a really bad temper and has done some horrible things to me and always the children. Additionally, I kept a journal of each day he missed his scheduled visitation over the past 9 months and he missed 78 days of scheduled visitation. I honestly don't think the judge would take my kids away but there is always a chance. Do you think if my house sells that I should go ahead and buy a new home 20 miles away or WAIT until the court issues an opinion and just rent a place until then. My attorney said the court case could take between 4-6 months.